W6PQL Amplifier's intermittent RX issue troubleshooting and sequencer adjustment

 W6PQL amplifier is great modular amplifier design. Since I had homebrew assembled in 2015/16, it has proven very solid and reliable. I have some issues with Directional coupler and detection of signals to represent reverse power accurately as per Jim's design. However, other than this aspect, i have used the amp in many contests and activations. Last year(2022) during CQWW CW contest, I realized that sequencer is slightly slow in switching back to RX from TX mode. Some of the stations I did not copy either first character or sometimes missing dit or dashes of the first character. This was not serious issue, but anyways, once you know what adjustments to do internally, you tend to tweak it towards perfection. I tweaked the timing so that its faster switching in sequence. 

During the CQWPX SSB contest i did not realize any issues. And after all SSB signals are delay start by human nature of speaking into mic. Also, problem of hot switching might have started during the WPX SSB itself , but did not come to surface. During WPX CW, My entry was bit delayed due to exhausting MQTH work till previous day late night and tr avel related fatigue.  VU2VTI was the early starter at VU2REC club station for the contest. When I started on the bands, at first it seemed all ok. But, suddenly started feeling the RX is weak sometimes and delayed to full signals. I thought it was due to some ionospheric disturbance. But when it continued for some hours, i sensed it unusual. Asked VU2VTI to be on my system and run the contest for few minutes. He confirmed that it is unusual and something might be wrong with my Amp or Radio. I then disconnected amp from the path and observed no issues with RX drop. This confirmed me that Relays inside the Amplifier might be damaged. No time to fix and no spare relays on hand. I packed my amp to carry back and continued the contest with TS590 barefoot.

Back at home, after opening the amplifier lids, first thing visually checking the three LEDs in sequence i.e. Hold off ALC line, Trigger Relay line, Release ALC line. Initially it was almost instant, I adjusted PCB variable pot to have some visible lag between the events. There was no RF input given to the amplifier, all testing was done using a SPST switch to PTT in RCA plug. This allowed me to rapidly check the working. Next came checking the Input and Output  Relays. While input relays typically take less than 10Watts or less in the path (my drive power), output relays handle upwards of 350W or more.

I had a hunch that output relays might be the issue due this factor. While switching PTT line, keeping my fingers on the relay, I sensed no movement in the output relay. Thanks to modular design of the amp,  i could desolder the output relay PCB and test it separately. Found that relay coil was showing higher resistance and was not energizing. This is Omron G2RL-1E relay and fortunately, i had few of them in my spares. I did replace the relay and test OK.

This incident has taught me something very important about sequencer lines and never to be too greedy beyond the design specs. By properly adjusting PTT delay for Amp (i.e RF hold back after PTT switching), we can safely control the TRX path for signals. Typically 100ms is what W6PQL suggests (Hold ALC line + 50ms delay+ trigger relays+50ms delay + release ALC line). 

Now will have to wait for next contest or event for my setup testing in real situation.

Hope this helps someone in similar situation.

VU2XE

CQWW CW 2022 VU2XE SOAB LP - Confusingly amazing!

All my limited understanding of HF propagation went on toss :). how much should be SFI for great openings on 10m?.  SFI was 109 over the weekend and N0NBH solar widget showing 10m band as poor with A =10 K=4 etc and I did over 600 Qs just on 10m for the weekend!. I am really confused but even more amazed with what we didn't know happened at bottom of HF comms pyramid!. Is that Nature's miracle to keep Man amused and grounded. 

Background:

Last 10 years in contests, I have not experienced a condition where Qs poured this heavy. Really.. there was no time to pee, even gulping water seemed difficult in midst of that high rate hours HI HI! and this is story for me of  more philosophical revelation and may be a start of new era in Radio contesting years. A story of learning, struggling over years for location, evolution in antenna designs to suit locations, right frame of mind and finally saying - "this is all I had, now what?". - take it easy !

Last month, myself and VU3SPD - OM Vatsa did low power Multi Two SSB contest from this hotel in the northern outskirts of Bangalore. Location was quiet, radio friendly. Though it was not at high elevation, HFTA showed good signal probability at hotel's 30 to 45feet high terrace. I was suffering from heavy cold and throat infection for the voice contest. Some heavy tripping of W6PQL amp due to SWR issue lead to HP Blade ESP120 DC power supply problems. We made decent scoring of ~650 Qs. For last few years, I have traveled 350km to beach location near my native for CQWW, but this time due to MQTH, decided to operate from this known location nearby.

My amp was not giving out more than 150W with another standby power supply due to efficiency. W6PQL suggested to reduce amp VDD to 40V which can increase BLF188XR LDMOS output to 400W (for better efficiency at lower input power). I could not adjust the power supply below 46.5V due to limitations in that SMPS design. So amp was kept aside for CW contest. I started preparing my mind saying my highest till date was in 2015 that too with 50W power and now this 100W from rig is 3dB higher. So scoring goal can also be higher than that of 2015 to start with.

This also allowed me to relax, as when I travel with high power gear there is always some anxiety around local electric power issues, extra weight, SWR etc. I had done a presentation during Hamfest India 2022 where I mentioned about "Pyramid of HF Comms" with 5 layers. At the bottom is Ionosphere. My point was - to make comms successful, Operator at top is at the mercy of Ionosphere at the bottom and all other layers are instruments in between. With our limited understanding of Nature, we have to be in submission mode to be humble and accept what comes. - a hard learning over years. So we have to put efforts, learn and advance, but always have to be cognizant of the fact that we are tiny particles in larger context of Nature and what we don't understand (call it miracles?)  

(Disclaimer - many videos, images, background music used for this educational presentation are from youtube, pixabay and other channels. All credits to them only. Thank you in advance for your shares)

Setup

This contest seemed like summary of what I presented in text book style. My plan was to keep it simple, using homebrewed triband hexbeam with fishing pole and dipole for 40m. 

Soon after hotel checking-in on Friday @7AM, I got to their terrace to unpack all antenna wires and coaxes. First was to set hexbeam. Clock work starts with my lightweight mast and center post assembly. 

Many aspects of this were designed only for temporary setup and knowing that we have to be ready for any issues. One hour was my target and I did manage to complete assembly within that time. But tuning took another hour for SWR match.

During assembly one of the spreader leg got fractured and it was repaired on the spot with a small PVC pipe section lying around. 

Yeah. Finally it is all done with one antenna by 9:30 AM. Does not look perfect arc, but it seems performing. All parts used in the project were locally sourced (Decathlon for 5m fishing pole, hardware shop for PVC pipe, 1 sqmm wires, vinyl base plate, L angles, worm clips etc.)

Now for 40m antenna-

Few days before the contest, I had modeled 40m dipole (4nec2) with one leg bent towards floor at 45deg, other in horizontal and checked adding a driver element. It all showed good 2.5 to 3 dB better gain and FB of more than 20dB. So why not carry wires?

There were two levels on terrace. One ~30ft high was adjacent to room and another above the room at 40ft. There were few wall clamps permanently fixed on the south sides which were used last time for spider pole support. This time, it was easy decision to use the same. Used 9 sections of 12mtr spider pole, attached choke at 7mtr point and dropped a thread from 9mtr point for holding director element. First tuned driver element to 6.88Mhz with director decoupled (dropped to ground). Then raised director at 15 feet horizontal distance  from driver (distance plays role in FB and SWR which was adjusted to get best). All this took couple of hrs. 

By lunch time, I was done with all terrace antenna work. My friend VU2CDP was also at an excellent field location near Pune for the contest. He kept chatting with me on his progress and challenges there. 

Afternoon, I went on to setup working station. I also tried amp for power output with standby DC supply and decided that additional 50W is not worth keeping extra hardware on the table and dropped to barefoot 100W with my TS590.

Some more fine tuning of antennas for SWR and test of FB was done in the evening.

Desk looked neat and promising for upcoming contest day.

Contest-

As in my 2015/16 contest, first few hours seemed to determine the outcome and it did so here as well. First session on Saturday morning till breakfast at 2:30 Zulu ended with 59 Qs on 40m. This gave me confidence that I may be able to beat my previous low power scoring. Then started on 10m with Japan. What a discipline in pileups as well!. It was like some traffic cop sending them one after other. Continuous Qs till 3:30Z. Switched to 15m at 3:30Z with JA pileup till EU started popping/taking over around 4:30Z. Pileups on both 10m and 15m alternating when one slows down. Continued till 12:30Z on these and then switched to 20m. 20m was comparatively slow paced till 16:30Z with many NA popping in between. Whole night was spent on 40m with a 4hr sleep breaks. Later VU2CDP informed me that it was prime time for 40mtr. But I could not keep myself straight for both nights during that time. First day closed with 1K Qs in total. 

Sunday started with good Caribbean multipliers on 40m such as V26K, PJ4K, ZF1A, PJ2T. Then kept runs toggled between 10m and 15m as per run rates. Maximum I could handle was 120 Q/hr on 26th. In between I thought "oh lord, I asked for good conditions and you are just pouring". Day2 also followed the same pattern of follow the Sun i.e. 40m till 2:30-3Z. 15/10 for JA till 5Z and then continue with EU on these bands till 12Z. Around 12Z, started checking 20m. Interestingly on day 1, 20m was not having big signals till late evening local (i.e 12:30Z). My reversebeacon.net spots showed good signs on all bands. With low noise floor, Except  sometime after evening greyline, I could copy much weak signals. Some of those signals didn't even move the S meter needles on TS590. I closed my contest with excellent team at A44A on 40m at 23:57 completing my all band contact with them.

In no time, I was packing and by 2Z  was on road back to my home reaching safely back and logging to MQTH remotely!

What are the learnings this time?

What worked very well-

Multiple field ops in last couple of years, helped to refine the go kit for contests

1. Filter sets, Amp, Radio, Ant, Tools all in their respective bags
2. Antennas are mostly for the location & situation with some enhancements
3. Most of the clamps do not require any tool, use plastic butterfly handles for quick fixes. 
4. Minimal waste of plastic and ties -replacing with rubber tie wraps (inspired by bongo ties). 
5. Understanding of antenna models and tuning procedures for multi element yagis really helps in adapting to location
6. HFTA is a boon before reaching the location, do physical recce for noise floor and friendliness
7. Keeping the relaxed mind all the time and sharing fun bits with buddies during ops really boosts morale
8. Packing from one contest is preparing for the next one. Keep the kits in shape after each contest  - check wires/coax for damage, clean connectors, keep tab on spares (nuts, bolts, solder, guy ropes etc) 
9. Carry extra chokes with SO239s. it helped me to resolve RFI issue of USB audio connection drops for QSOrder

Out of all 5 layers of pyramid what matters most ?- 

While multiple ops optimized instruments over time to some extent (rig, antenna and location choice), Top of pyramid - The Operator (who seems to be understood and under control ?) needs more refinement and higher level of respects to The bottom of pyramid - Ionosphere (The most illusive and not in control !) 

Operator - Need to work on optimized schedule for night time shift, multiplier hunting, be smart to apply ideas for the situation

Ionosphere- We can only have general trends of signal path. But what will happen on contest day, no one can predict. Impossible happens within minutes. We are just witness of  fine balance between Sun and Earth spheres

Operator is at the top of pyramid but he is really at mercy of bottom of the pyramid - The Ionosphere. But when all things go right CQWW CW 2022 happened to VU2XE setting higher bar for next time!

What about you? Did you experience the magic? Hope you enjoyed the thrill as well..

DE VU2XE Kiran

Protect connectors with this simple Hack!

 Amateur operators use many type of connectors in the shack and in the field. One of the most common connector I use is UHF. When they are used in outdoor transmission lines, we normally waterproof them using rubber tapes, insulation tapes etc. While they are not in use, if they are left outside in garage or workshop, dust/moisture ingress will deteriorate their performance over time. Often, we should use contact cleaners before taking them out for use.

In the past, I have used plastic caps (MX in India sometime comes with such caps) and metal threaded dust caps as well. But, they are hard to find in India. I wanted a easy solution for making quick n reusable protection for many UHF connectors I had in my box. This is a problem while carrying devices to portable locations as well, especially unprotected PL259 connectors take hit when uncoiling coaxes. 

Here is what I came up with available heat shrink sleeves. Yes they are not good as threaded caps, but 

1) Keeps connectors from sand, dust, water ingress

2) Reduces wastage of insulation tape during transport or uncoiling coax

3) Can be quickly made in the field too!

73s 

VU2XE

CQWW CW 2021 - Multi Two VU2XE and VU2CDP

Note: 3830scores.com has operating notes on this contest:  https://www.3830scores.com/showrumor.php?arg=lRabzesimgvgD

Just after my CQWW SSB attempts at Mulki in South Karnataka coast,, VU2CDP got in touch with me for a much serious multi efforts. I agreed on a low key efforts. We had limited automation resources and hence settled on multi two format just to have both of us operating. Having decided about participating in the contest, next came from where? and obvious choices would be close to Sea having good property space to put antennas. Last few years, I had been scouting for quiet radio places to operate contests as I was restricted at home QTH. One place out of my scouting experiences comes to my mind each time was near Coastal town of Udupi (my first experience at this place with VU3NXI in 2017 posted at http://kiranpadiyar.blogspot.com/2017/12/lowband-hf-experiments-near-coastal.html). We shortlisted that river estuary point homestay(AirBnB) near Udupi with many coconut trees and comfortable self service. It was convenient for me to travel from Bangalore and for  Deepak to travel via overnight train from Mumbai as well. Also, I had kept most of my equipment at my native place which is 80Km southwest of this place. So logistically it was convenient.

South West

Next was antennas, Deepak suggested to have mono banders to reduce interactions. Though my Triband VDA antenna with Triplexer ( homebrewed VA6AM design) and High Power BPF(homebrewed PI4CC design) set I had would have sufficed, There was some tuning difficulty observed last time and I thought it is better to avoid any component failure probabilities or delays due to unconventional antenna designs. So, I got to design  monoband VDA using 4nec2 software with locally available 1Sqmm PVC housing wires. Based on earlier experiences with VDA, I made center cross joint with plastic cutting boards, Coax connectors to go with PVC end caps etc. All three VDAs were designed and wires were cut/prepared for assembly. For RFI choking, we used coax clamp ferrites. For 40m, I had half square array and Spitfire prepared on earlier trips. For 80m, I prepared vertical with two elevated radials.

North West view

Our Homestay was only available from Friday and we wanted two days prior to the contest. Owner obliged by letting us to use the property for putting antennas on Thursday and later they allowed to check-in on the same day as no other guests were present. We found that, two days are very minimum for setting up such station. 

I had reached Udupi on Wednesday for arranging all antenna stuff and doing prelim work like PVC cross arm assembly, cleaning up Coax connectors etc. On Thursday morning, VU2CDP arrived from Mumbai train and after a short rest/breakfast, we proceeded to homestay site. We carried only antennas, ropes and coaxes. Owner had arranged for Coconut tree climber for our antenna hoisting. We quickly got into action with location for VDAs, vertical and dipoles. 

Kiran at far end maneuvering rope for 40m dipole

We chose tallest tree ~60 feet for 80m vertical (it was faithful one which supported our fan vertical for 40,80 and 160 on last operation here), a ~50 feet one for 40m and one more as standby. Within a hour all pulleys with ropes were tied to the trees. We then got in assembling VDA antennas 20m first and then 10m and finally 15m. 20m tuned on dot on first attempt, but later we moved the antenna farther to avoid tree leaves touching the elements and changing SWR.

VU2SBJ Sri, VU2CDP Deepak, VU3DMP Chetan
and VU2XE Kiran at Manipal

VU2CDP with VU2BQN Dr.Manu and VU2NJN Dr Soma of MIT

By afternoon we were done with 20m VDA and 80m vertical. We found that we need more coax and requested our friends VU2SBJ, VU2BQN for help. They arranged for additional Coaxes. By evening time we were ready with 40m Vee dipole (I prepared this dipole with wires of halfsquare ) at around 50feet apex and ~25feet high leg ends. Next day we completed 10m, 15 m VDAs and final station layout setup as well. During the final testing, we had VSWR swinging with 20m VDA. That evening VU2SBJ, VU2BQN and VU2NJN visited us. We figured out a faulty barrel joint and fortunately VU2SBJ had one extra barrel which sorted the issue.

VDA Coax feeder arrangement with PVC cap

Then we were left with N1MM network, where we struggled a bit as interlink was not happening. I called VU3NXI for help and bit later figured out that netbios name had to be placed in Network status-> Edit Computer Address section of N1MM software. This was not necessary in last month's contest as it was detecting other computer automatically. So all sorted, we took a breath. 

Now, It was all upto Sun god to grace some flux on earth and of course He turned his major Spot region and flares this side for increasing SFI over 100 on time for contest!

N6RK Loop for 80m

20m VDA Tuned at once!

 

VU2XE and VU3DMP Fixing 15m VDA

All certain done, we were ready for the contest on time. We decided that we both will run at around 200W only to avoid voltage drops. Both of us got to bed by 11PM (contest starts 05:30 AM local for us). I am unsure whether we got good sleep or no, as the restlessness to get on radio had caught us hard.

Contest morning - started very slow for us, But we noticed that both of us could not run with amplifier even at 200W. So one had to be barefoot. On first day, I went barefoot and Deepak was on his K3+KPA amp - running. This was major setback, because we found 15 and 10 opening at same time in the afternoons. We could see around 1200 Qs by that night. I took early time off at night at about 10:30 PM and Deepak kept on Radio till late morning. 

Next morning, I got chance to run with 400W on my W6PQL amp, I continued most of the time running 15m. 10m was again very good that day and Deepak could not use amp due to voltage tripping issues again. We might have lost working few hundred Qs due to this power issues. We had tunnel opening to NA on second day which gave us a bump multipliers. PY, LU stations were having multiple clear opening to VU and helped us in boosting scores when QSO rates from EU were low. We did not find much JAs in our pipleups this time even during our morning 15m lookouts.

Our VDAs worked exceptionally good as they were only few feet within saline water. Its directive gain and F/B ratios were just amazing. On low bands of 40 and 80 we could hear signals even if someone whispers hi hi!. Overall we made 2735Qs which is very close to our set goal of 3K QSOs, and very satisfied with operations. 

End of contest celebrated with glass of buttermilk!

Few takeaways:

1. We noted that we could have used automated switching to jump on other bands quickly to reduce time lost etc. This contest had many coax changes and mistakes during such change over. Probably its time to put my High isolation A/B switch matrix to use in next one.

2. Simple dipole on 40 and vertical on 80 were good enough choices. Probably next time we will look into some additional directional gain to these

3. Power Generator is must at such portable location for bigger scores. Though we could run on barefoot and one amp, we could not benefit from simultaneous band openings. W6PQL amp uses HP blade ESP120 supply which has broader voltage range than KPA500 which seemed to trip with voltage drops.

4. We need to figure to connect local router with some internet connected Wi-Fi device for cluster spot feeds and real-time score reporting. This time we had to connect our laptops to phone to refresh scores etc. and then connect back to local router. bit cumbersome.

5. Overall getting better with portable contesting going on air time by travelling lite, simple layouts, efficient station etc.

Our equipment this time:

• K3 with KPA
• TS 590  with W6PQL Homebrew amp
• VA6AM Homebrew Low Power Filters for 20-10, W3NQN filters for 80 and 40m
• VDAs for  10,15,20m
• Inverted Vee Dipole for 40m 
• Vertical with two elevated radials for 80m, N6RK Loop for Rx

Our quest to improve operating continues. Hope to see you in the next one!

DE VU2XE

Triband VDA antenna update (V2)

 Last year during CQWW SSB (Oct 2020), I had tried to tune my own designed triband VDA antenna. Whatever I tried, it seemed that antenna was not tuning or getting out well. Youtube video on that effort is at https://youtu.be/tJb-NoXO6V0

Couple of months ago, I was pondering about the issue with VDA and realized that my design was not considering PVC jacket dielectric loading (velocity factor). That  made me to load the model(4NEC2) with PVC jacket and check once again with same dimension. Oh. My.. Yes, I was way too off from the design frequency and no matter what I did on ground, it would not have given right results. 

So, a month back during Covid19 native place stay, I carried the VDA to be installed at my garden and check with PVC adjusted dimensions. And I was finding the spot on tuning. I know, triband on a single pole is compromise due to spacing requirements and height above the ground etc. But this is something I could live when Sea is washing its base, when I travel solo etc.

With this test done at home, I got opportunity to test it right on the beach when I was invited me to operate at Kapu Lighthouse AT8KLH near my hometown. It is a week long activation of lighthouse with many events and teams planning to operate from the location. I did quick recce of the place on my way to Udupi where I had kept most of the cables and poles from last WPX contest. Found very friendly neighborhood and a school on the beach next to lighthouse - very ideal for the operating. There is greater collective story to be compiled once the activation is complete. I am sharing my short 2 day participation experience with VDA.

Putting any antenna on beach during monsoon season is bit of pain, we took 2-3 hours to just put the antenna and secure with guy due to heavy rains. Once it was erected with help of Lakshminidhi VU2WFN, SWR plots were checked to be on CW portion of the band where myself and VU2VTI Murthy wanted to operate. Though I had carried some heavy filters etc. to operate multi, we could not due to lack of electric power at the premise.

Anyone who has operated the VDA from right on the water edge know how signals come. I can make a quick contrast with eating food right out of frying pan (still sizzling) vs somewhat cold but still fresh on the table Hi Hi!. Signals with incredibly low noise and crisp right out of the operator's shack on the other side of the globe. We made a 650+ QSOs with many breaks and change of operators etc. till we closed later evening on 15th. Epitome of thrill when one could be in the center of massive pileup and in control of it!.

Following is the 4nec2(freeware) design file if someone is interested in replicating/improvising.

https://drive.google.com/file/d/155F-yHVCxiO9XVuinu8rqDsIFrOxilXo/view?usp=sharing

There is lot of opportunity to optimize further especially for F/B ratio. Here are some plots from 4NEC2

Note: This VDA requires 10mtr tall support (I used 12mtr spider pole with last two segments collapsed). At the Cross section, I used a cutting board material with drilled holes for wire ties. For cross arms (total length of 2 meter), I could have used PVC pipes, but I had couple of Caperlan fishing rods (1 meter collapsed length). This antenna did not hear anything from back. Just to note, there was a small ridge (15ft tall) at the back side towards south east/east. which might have helped in reducing noise/signals from back. Following reverse beacon report and QSO stats shall summarize the efforts well.

Website for AT3A contest and all homebrew projects

I have created a new website for compiling all the projects and tiny contest efforts:

https://vu2xekiran.wixsite.com/at3acontest

It all started with couple of small projects and contesting is means put those projects under real test. AT3A was the call used by me in CQWW contests in 2018.

Cheers

VU2XE

CQWW CW 2018 as AT3A

Background:
Quest for better contest time participation was/is always on. Many requests in common interest groups went in vain for group operation due to one or other problems. I thought of preparing a tiny contest station at my native place near Mangalore on the south west coast of India as i had no hope at my home QTH. So the idea of AT3A was born few months ago. Unlike serious full-time contest station, this would be visited only few times a year and some restrictions on antenna placement and noise from proximity to small town area.

Many visits to this place which is around 320 Kms from Bangalore were made to fabricate and establish antenna support system, carry equipment etc since June. WPC permission for QTH change for 3 month duration mainly to operate contests had come on time. However, till CQWW SSB i could not get station up. When setting home station, one will not notice efforts required as it is over period of years that we develop efficiency. Now trying to achieve the same type of efficiency at a new place in comparatively short few months became a daunting task on self. All certain done, CQWW SSB last month could not get me much scores at all. My TS590 RX was suffering from sensitivity issue of some sought.

Sorting out TS590 RX was on priority. I had to check resources websites, fuse blown issue etc. However, troubleshooting took me nowhere and probably requires some more efforts and help from techie friends.

Equipment: 
TS590 with SDR play as pan adapter
Homebrewed W6PQL Amplifier
Hexbeam
Vertical and inverted L for 40 and 80

Preparation:
Antenna support base was around 25 feet with plan of around 40 feet tilt pipe for Hexbeam. During the first lift, the pipe started developing bend and then we had to cut the pipes to go only upto total of 33 feet from ground. For SSB contest, verticals were not on focus. But for CW contest, I placed 40 mtr vertical and 80 mtr inverted L on same spiderpole of 40 ft. This antenna was located at backside of house on old cowshed building. Getting to roof was a problem as it was made of clay (Mangalore tiles). Many of tiles were broken in the process of placing antenna and tuning :(.
On the first go these verticals seemed to work fine. but suddenly they started to show higher SWR. Changing Choke and Coax did not work. Just a day before contest, i pulled back vertical wires to check and found that at around 20 feet above from base, wires came very close and fused together to form short (looked similar to twinlead wire). Ahhh.. This made me to remove 80 mtr wire and limit operation to only 40mtr on that vertical pole. With 4 elevated ground radials, all SWRs showed OK and ready for Contest!. We had huge thunderstorms and lightening strikes to nearby place in the evening followed by unusually heavy rains at this time of year. Around 500 mtrs away electrical lines got cut off with a transformer malfunction. Fortunately, nothing happened to the antennas and station i had placed and power restored at my QTH.


Contest Day 1:
It happened to be day after major festival (Full moon day in the month of Diwali) here. All of our small town was decorated with running lights and loud music was playing most of the time etc. Major blow from RX noise  as I could not hear much during first 12 hrs.There were series of power outages interrupting any possible run i could have made. Total QSOs for the day were low around 370 with mostly S&P.

Contest Day 2:
This day started on much better signals and first big run came around 7UT to 9 UT and then second best run between 11 to 14 UTC. Entire day 20 and 15 mtrs were wide open. When NA stations started appearing around 12 UTC on 20mtrs, they were similarly strong as EU. Band spectrum was brutally occupied.
After 14:30 UTC, signals started fading on 20mtrs and 40/80 showed increased conditions. Day two added around 630 QSOs.

Summary: 
In total, I did just over 1000 QSOs with high power category running around 400Watts. This is still 200QSOs lesser than my 50W low power contest entry of 2015 (https://www.3830scores.com/showrumor.php?arg=oHaXzofymaivL). Lot of rooms for improvement for sure.

Following is the final count:

Band     QSOs     ZN   Cty  
    7      267     21   71

    14     384     19   53   
    21     355     19   56   
    28       3     2    3   
 Total     1009    61   193

Claimed Score: 710,438

Thank you all for the Qs and see you next time

VU2XE

Some highlights:

Traditional Kerala drummers ("Pancha Vadyam" -5 instruments) performing on the street near QTH for festival few hours before contest:

My antennas:

Band overflow during the contest as seen by my SDR Play - not a Hz spare :).

Terrain Analysis matters ! - Correlation to Contest Scores

Couple of years ago my neighbourhood started changing rapidly. Once used to be a 5 Acre coconut grove just 100 Feet north of my QTH was grounded over a week's time. It is the demolition monster drive similar to the one in Avataar movie. Along with hundreds of eagles and birds who lost their home that day, I had lost hope on my peak DXing days! After hearing that it was mega project with 360 apartments spread over 5 blocks of 18 floors each, my spinal felt like just out of frozen ice :(.

One of my senior ham friend did help me morally a bit providing what was unknown to me then called HFTA. That analysis stated that, I will loose my sight in the direction of this building which is 320 deg to around 30 Deg north. And it happens to be prime area for contesting and DXing over the poles!.

Recently I purchased ARRL's Antenna handbook. The CD which came with it contained HFTA software written by N6BV. I got hooked to it once I learnt how to use it. It opened up new paradigm for me on HF ray propagation and study the effect of stacking, antenna height with respect to immediate terrain. In combination with K6TU.net 's excellent terrain data service. I started doing many hours analysis of locations I had been recently as well.

CQWPX CW 2018 was the first contest after the high rise got completed. This contest was to test my understanding and vola... It really did reflect what was predicted. Signals were way down than it used to be. Partially overall HF weather also had a play I am sure.

Following are the graphs of these changed conditions. My terrace is at 140 ft level and around 150 ft from me is 180 ft tall building.

I plotted the graph with antenna at popular 50ft level on flat reference ground(Green), 150Ft level without the highrise (Blue) at 330 deg and current condition with Highrise (Red). Purple bars show %ge times signal arrival based on statistics.

We can see at 150ft level, there were deep nulls with signals below reference level. But then, there was surge in gain at low angles. No wonder why I used to catch K3LR  and other long haul DX before many could hear them. But see what happened to me now. Red line barely rises above reference and gain is no where near compared to peak gain of 16dbi at 7 Deg I had earlier (down by 15 dBi now i.e 2.5 SUnits or more). Less of make and lot of break moments.  We can also see that between 3Deg and 13 Deg there is statistical average of 5% or more signal arriving. All these chances are lean now.

Following is similar graph for 15Mtr band.

And this reflected in my score. I used to have restricted grade earlier and best score was in 2015 CQWW CW with nearly a million points. I could achieve this with 2 element Hex and 50Watts only.  End of 2017 in the same contest I could only manage 600K points, that too with 400 Watts and Spiderbeam. i.e. effectively 9dB (due to Amp) + 1.5 dBi (avg spiderbeam increase) = 10.5 dBi gain.
This gain in forward direction was negated by the high rise on transmit. On receive it is only 1.5 dBi, which will be of no use as building is blocking most of the low incoming signals. In total effect, i may be sounding similar to my restricted grade signal to DX, but if they respond and signal rays arrive at those angles, I will never hear them :(.

Lastly, 150 Feet height  was not the best in both the cases either. One can see deep nulls at some elevation angles with good %ge of signal arrivals. Most of the contesters have mono bander stacks just to overcome those deep nulls. Following is stack of two number of 3 element yagis at 90 and 120 feet.  See how it moves the nulls to right making space for desired angles.

Today, I feel I know many of these wonderful areas of propagation due to software such as HFTA, but handicapped to try the improvements. I am hoping that in the future, I can go to right places and put portable stations for contests!

Cheers
VU2XE Kiran


Disclaimer: As usual, this blog and its content is only based on my own personal experiments and observations. I share it for fun and in hope to kinder some curiosity. I am no expert in these areas. Sometimes, my conclusions may not be accurate. For accurate information you are suggested to look out for original sources and experts in these areas.

CQWW CW 2017 - 40mtr was the ruler this time!

Last year CQWW, I had discovered value of low bands during the contest and wanted to improvise one band at least this year.  Well, there was great news on propagation with improved Solar Flux with new sunspot appearing on Sun's plate. So hope for higher bands as well. However,it is "the" contest time :)! So...

40mtr authority!

After much of background work talking to many hams in VU and reading some DX articles, I thought of settling on 40mtr vertical. However, I was having issue with listening. VU Contest group member VU2PTT extended his help by providing me a kit of N6RK loop components. Few weeks before the contest I started experimenting with this combo first with only vertical and then fixing N6RK loop. I could hear EU very well, however, W6 stations reported deaf on cluster during our grey line period. I was really amazed at the same time by one another ham from Bangalore working W stations (update Jan 15 2018: Topband reflector discussions on some using NA based SDR for RX and making QSOs from VU. It was no surprise then for me that I could not hear anything on my antennas!). Also there were hams in Kerala (they have location advantage and some use large beams) working US on 40mtr without much difficulty. So there is lot to improvise to dig out layers of callers in future as well. For now N6RK loop was great booster to me on getting that 2nd tier stations.

W6PQL amp got extra breathing space!

Now with one additional band in relatively good condition, I was happy and prepared. During final station check on Friday evening around 10 UT, I got a shocker with Spiderbeam behaving badly with varying SWR. Panic rush to terrace and tightening balun and wire lug contact nuts seemed to resolve the matter. 

American pan cakes to celebrate morning  Caribbean Qs

Contest day morning provided good start on 40mtr and then after around 5UT, turned to 15mtr to buzz that for next few hours putting more than 350 Qs by 10UT. There was no sign of 10mtr having any signal which limited any possibility of big runs. By this time, I was hoping to switch to 20mtr and try to put another 300 before switching to 40mtr at night. The problem with Spiderbeam SWR contacts surfaced again and had to suspend the 20mtr operation till next morning as our apartment security would not allow us to enter terrace after dark!. Bit disappointing, but hope lingered around 40mtr to make most of it. And, sure it did so running for next few hours till late night around 20UTC. By this time, QSO count had crossed 700. I could make clear difference from operating with only dipole last time vs with vertical + loop combo this time. Stations which used to be in shadow of noise earlier emerged in clear this time.

Desi Chinese Soup
kept me going for mults!

Second day, I went and fixed contact issues around balun where there was some residue of rubber around the washer and nut. I had planned outing with family rest of the morning hours. I may not have missed any openings, as when I returned around 9UT, there was no sign of 10mtr opening. 15mtr and 20mtr SnP started on slow pace. Did not get much response to running other than K3LR, W3LPL, ZF9CW and few other North Americans coming back. However the signals were not strong. Partially, the new high rise building which has comeup north west to north east might be the cause as well. As per HFTA software, high rise is cutting down low angle elevation signals which are crucial for NA shortpath from here. Finally, I made some drag towards the end on 40mtr before closing early at around 19UTC after crossing 1000 mark.

There are lessons each time. 

1. Use of UP and Down arrow functions to control RIT during Run pileups. This is very nice feature of N1MM logger to dig out stations from the pile.

2. Improve reception to the max before turning the power to max - many low power and QRP stations located in quieter locations (and probably with good RX antennas) can hear and call you. 

3. Better yourself at usage of SDR waterfall and spectrum in assisted mode. Anchoring for the run or to identify weak multipliers it can be a good tool. Also if you are using SDR, try SO2V function, i tried to make it work but did not take it much further. Unlike SO2R, SO2V does not require second amplifier if you are making jump on the same band or have amplifier with auto band switching for the multipliers.

However much one is prepared, expect some issues. Low bands are really rulers in these times. Hopefully, I can add another band - 80mtr next and even better receiving capability.

Thanks all for the QSOs.

73s

VU2XE Kiran

Following are the detailed count from contest log:

Band     QSOs     ZN   Cty  
    7      475     24   71

    14     150     17   46   
    21     370     23   63   
    28       8     2    2   
 Total     1003    66   182

Score: 632,896

Link to last year’s blog post: http://kiranpadiyar.blogspot.in/2016/11/what-got-me-here-will-not-take-me-there.html

What got me here, will not take me there ! - experience from CQWW CW 2016

Writing this blog post as I just return to normalcy of life out of the biggest CQ contest of the year!

Learning a lot from this year's contest, thought of sharing it will readers here. Hope you will enjoy..

Last year by this time, I had just given license upgrade exams and was awaiting results. As VU3KPL, I had distinct advantage of the low power (50W) and my operating style which was mostly Search n Pounce (S&P) during the contest and intermediate runs on the higher bands. This skill was built over few years which gave me a lot of frustration and fun at the same time. Frustration when stations could not hear me well and fun when my 50W made a big impact all over for short propagation duration.

This time as VU2XE, a minimum 2 S unit difference was available with me, but....

1. Power to run is great , but do not forget about S&P for juicy multipliers:

Difference being, this time a perfectly working LDMOS amplifier which I could drive to VU legal limit upto 400W, but overall lower propagation conditions. This amp dragged me into running more, and less of S&P. Some moments during the run were so fierce that I could not pick calls as fast as I would have otherwise. This might have driven some high speed callers away and bringing my run lower than 120 Qs/Hr. Not bad in usual case, but during those narrow propagation windows we observed during the weekend, it proved bit frustrating. These runs got me into another mode of "wanting more" on run whatever it may be, forgetting the juicy multiplier search elsewhere.

2. Turn off DX cluster window if you are not using it from the start:

Important aspect which I did not consider was finding some mults using cluster spots. Never used spot window effectively because of the rush during the contest. I have to be frank to admit that, I only used it while parking my run frequency. It is considered by me as using assistance, so logging as Assisted mode!. If you turn on cluster window, do some justice as mentioned in point #1 above

3. Propagation may swing rapidly and get the best out of it:

A pattern observed during this contest was about 20m band conditions. In recent months, 20m normally stayed open till 14:30 or 15:30 UTC to Europe and then only to NA and Caribbean for some more time. This time, it closed to all directions by around 2:30 UTC or so. In small windows towards NA, there were big stations calling me such as K3LR. But they were RST 559 or so. Some stations, i could hear trying to make Q with me but vanished under QSB :(. 

On the other hand, 20m showed best of its colors to me during the day time. I think it must have been open since mornings, but my operations only started after 9 UTC on 20m.

4. Lower Band antennas are must:

We are entering into no excuse years. One who concurs 40 and below will be on the winning race for sure. I did not have great antennas there. With OCF dipole and lower power, I managed 140+ Qs on 40m. There is lot more improvement on lower bands at my station required for sure.

So, these are some takeaways from this contest which is ultimate test for contester's preparation, skill and station quality (only big variable being propagation!)

See you on air

Kiran VU2XE