Monday, November 9, 2015

More work on my old FT726R

As previously mentioned  in my blog I thought I had fixed the sticky contacts on the relay in the 144MHz module of my old FT726R. The adjustments only lasted 6 months, so it was time to make a more permanent fix

I made a  long search for a replacement relay, but found none, mainly because of the non standard pin configuration. It was time to try another way.  I found some DPDT 12v relays in my collection of around the same size, but with totally different (normal) pinouts. It was not possible to drill new mounting holes for the pins, The only option was to glue it upside down on the PCB and put wires from the relay pins to the corresponding PCB tracks

Original Relay with cover removed after previous relay contact adjustments

Relay Removed

Replacement Relay hand wired in place

While I had the radio open i fitted an extra cable to allow an external preamp output to be connected  to the 2m module receive input, without the risk of transmitting up the back end of the preamp.
External 2m Receive Input cable(exiting module to left)

Sunday, October 11, 2015

RSGB Convention 2015

Went to the RSGB convention in Milton Keynes with G4BVY for the weekend. Very sociable event, catching up on the latest VHF contest news. Went to a few interesting talks; GW4DGU on the Gemini Amplifier design, (although being a commercial design no details were given) GM3SEK on "(RF noise) cleaning up your shack"which was all about RF noise and G4BAO on the physics of meteor scatter.

Got the WW2R DXCC cards checked by N1ND to bring my mixed total up to 200 entities, including some from the 1990s he had not seen submitted for a long time

Having heard the dinner speaker before, we went out to a local pub for dinner, reached via a 30 minute walk.The Chicken Makhani tiffin (served in an authentic tiffin tin set) we had seen but not eaten the previous month was tried and was excellent

Sunday morning attended the VHF trophy presentations to participate in the Bristol contest groups receipt of the Club superleague and G3MEH trophies. In the afternoon I helped out at the FCC exam session as an examiner, having got my credentials restablished (with the expeditious help of Amanda Grimaldi at the ARRL VEC) two days before. My last VE session was in 2001 while at Nortel.

All in all a very enjoyable weekend, encouraging me to complete some projects and start some new ones , like a 5B4AGN Triplexer

Sunday, September 20, 2015

Return to 70MHz Portable Contests after 30 Years

Having Completely re-engineered the 70MHz MRF151G Amplifier after the disaster in February , it was time to try it. The opportunity arose in the form of the the RSGB 2nd 70MHz contest. Again the Blorenge is no place to go on a Sunday morning , so it was time to visit Dorstone and again use G5NF/P

Having disposed of my pair of 5 ele 70MHz MET antennas 30 years ago I had looked for a portable antenna. I found a Powabeam 5 ele on the DX Shop web site, They had a lightweight version of the 5 ele , but that was on a round boom which I avoid based on previous experiences. So they made it on a 2 piece square boom so it would fit in my car (only just,... the elements are one piece!)

The K3 was used to drive the 70MHz Anglian Transverter then into the MRF151G. 160W was easily reached with 2W into the PA module.As the amplifier is so compact, there is no room for an LCD display on the front panel, so a remote LCD is used to display the Amp Status (flashbacks to the KLM amps with remote display). As a precaution, should I forget to Pack the display the error LED flashes an error code if there is one in the style of Harris TV Amplifiers

K3 and Anglian Transverter

Amplifier and remote LCD display

The band suffered from the usual QSB but some interesting DX was worked to the East and North. PA4VHF was the best DX at 671km

The good news is the amplifier survived the whole contest, and we got a runners up certificate. To do well in this contest you need to be well away from the centre of activity!

Sunday, September 6, 2015

5th Backpackers 144MHz contest

Having not done a backpackers contest and with a promising weather forecast it was decided to try it. Blorenge on a Sunday is a pain so we went to the AFS winning site near Dorstone across the river from Hay on Wye in England IO82LB

Using just the K3 with its 8W output and my (previously unused) portable F9FT 144MHz yagi some reasonable DX was worked as there was a concurrent region 1 contest meaning lots of EU DX. The backpackers continues for 1 hour after the Region 1 contest  (stupid idea!) which means QSOs are sparse/non existant during that period. The only getaway was DF0MU, despite many attempts

For a change we used G5NF/P. Two stations complained about the missing W in the callsign!

Wednesday, September 2, 2015

144MHz UKAC Sept 2015

Conditions to were not as good as the last event with the average distance being down from 226 to 216km, but more northern Multipliers were found to break the 50 barrier. Having decided not to use the MHP, as the K3 with internal xverter was good enough on its own, we ended up using it to join 2 coax cables as no barrel connector could be found!

Sunday, August 9, 2015

144MHz UKAC August 2015

Heading to the Blorenge straight after work I was greeted at the site by Driving rain and wind, not a great prospect. How wrong I was!
 Issues with The MHP cable meant that the Preamp and Anglian Transverter could not be used, so the system was quickly reconfigured 5 minutes before the start of the contest to use the K3 internal Transverter to feed the PA  and use the Transmit Cable for the antenna connection (the MHP fails to transmit)
Nothing for the first 3 minutes then it was wall to wall stations, a lot from mainland Europe. 83 were worked in the first hour, as many as worked previously in the complete contest. Conditions to the East faded out so we decided to try for multipliers to the North as GB3ANG was loud. No sign of life in JO03, IO64 and IO74 but GM4AFF and GM4JJJ from IO86 and GM6JNJ in IO75 called us with big signals
We ended up with 183 QSOs 48 multipliers for a total of around 2 Million points best DX was DK5QN in JO42 at 789km. The average QSO was 223km compared to the normal 184km.
Luckily the weather cleared by the time the contest finished. 

Pos Call         Loc       QSO Score Mult Total       ODX        kms
 1 GW0FRE/P IO81LS 181  41,207  48  1,977,936 DK5QN    789
 2 M0BUL/P   IO82OI  167  30,328  49  1,486,072 PA4VHF  652
 3 M1DDD/P  IO93CH 172  28,105  47  1,320,935 DK1MG   726

The result would have qualified for 2nd in the unrestricted section!

Pos Call          Loc        QSO Score Mult Total        ODX        kms
 1 G4CLA       IO92JL   234 43,096  57  2,456,472 DG7TG    733
 2 G4FZN/P    IO94JF   170 37,819   49 1,853,131 DK5DQ    662
 3 G4ODA      IO92WS 144 29,983   54 1,619,082 DG7TG    654

Thursday, July 9, 2015


After doing HF NFD a month earlier it was time to do VHF NFD for the first time in 25 years. I was invited to provide the 23cm station for GW2OP/P in West Wales along with G4BVY providing the 432MHz station. The station ran the Elecraft K3 with Internal 144MHz transverter driving a home built G4DDK transverter which drove my W6PQL  4 x MRF286 amplifier to 200W output (drive limited). The Masthead Preamp used a G4DDK VLNA. The antenna was a 44 element Wimo.

Takeoff SW over Caldey Island

The 23cm Station

The 44 ele Wimo Antenna

18 stations were worked in 10 locators. Best DX was GM4CXM at 479km.  Five beacons were heard Sunday morning. GB3MCB IO70 on tropo, GB3CSB (IO75) GB3DUN (IO91) GB3MHL (JO02) GB3ANG (IO86) all on aircraft scatter. I used the W3SZ AircraftScatter C# software which predicted very well and showed many more planes than I ever got with DL2ALF's  Airscout
One thing that did get my attention on the contest was that G4BVY's IC706mkIIg was able to monitor our 70MHz station. I had heard this was possible but never seen it in action. Seemed sensitive so will have to do it on mine. He said it only needed one diode removing