Monday, 15 June 2020

IARU TV Contest 2020

For this years IARU ATV contest I decided to get a bit more active than last years 2 QSOS and go portable at three locations :-


Left home at 0800 and drove the 84 miles from home to Walbury hill IO91GI (thanks to Noel for the opportunity to use the site while he went elsewhere) Having never been there before it was a bit tricky to find, but the photos from google maps Noel supplied helped. 

Having 7 TV bands plus 2m FM talkback setting up the equipment took a long time, At the start of the contest worked G8GKQ/P on all bands 432 to 24GHz at 54km.

Worked G8LES at 40km on 23 and 13cm and he received my signal on 9cm (he has no transmit on that band) 

Worked G8GTZ/P at 51km 432 to 24GHz except 13cm (equipment trouble his end).

Transmitted my signals successfully to G4LDR at 30km on 24GHz to 9cm during some huge rain storms which forced a couple of hasty retreats into the car. Could lock to his carrier on all bands but got no further than Carrier and FS lock.  Did have a two way on 13cm with him

Drove back home arriving at 2240


Left house at 0700. Arrived at cleeve common car park IO81XW at 0800 

As a new location the rules said I needed new contest numbers in the Portsdown 2020. No problem I thought, I have previously saved a suitable new set to USB drive. Imported them but subsequently not even the Portsdown touchscreen would respond. After much searching found ethernet cable and did a factory reset via SSH. Manually set all parameters. Lost 2 hours so no time for expedition to trig point for LOS 24GHz path.  Worked G8GTZ/P at walbury at 76km on 13cm to (surprisingly) 10GHz,   Just not enough signal for 24GHz.  Location getting overrun with visitors so left at 1200

Drove the 29 miles to Notgrove, IO91BV, a site that should have a good path to Walbury (and would not be crowded!!) 

Decided to change the contests numbers manually and avoid risk. Worked Noel at 67km 23cm to 24GHz. Signals were not too loud on DATV but huge on 24GHZ NBFM.  

Worked G0MJW with big signals both ways on 70cm and 23cms. 

Saw signals from G4CPE on 70cm but couldn’t attract his attention with my 5W Tried getting signals on 70cm to G3VKV but path too blocked locally. Good signals on microwave bands from GB3ZME 3 and 5 GHz but too late to work the M0YDH/P in that area. Did hear the GB3LPC beacon on 3.4GHz narrowband for the first time.

Sunday, 10 May 2020

GM3SEK Mains filter finally finished

Having heard about the GM3SEK mains filter at the RSGB Convention 2019 and seen the design on his  web site I had decided to build one. I gathered most of  the necessary parts after Christmas. The one missing item were cable ties with screw holes to hold the ferrites in place. I finally found some on ebay so set about assembling. I decided to fit a 16A chassis mount plug and socket on the box to make it more transportable, the mains input and the distribution panel output having connectors to allow easy disconnection

Sunday, 19 April 2020

WKUSB-SMT lockup

I have used winkeyers for many years now, ever since building a serial version board to take on the 3B9C expedition without any trouble. While setting up a WKUSB-SMT at the MW2I station recently it refused to respond after a run on 20m. It appeared on the virtual com port but refused to respond to the wk3demo or wk3tools programs. I thought a reset was needed, but the manual was not very helpful as it suggested hitting the reset button when connected to the keyer, which I could not do. So I left the problem and substituted the spare winkeyer a  WKUSB-DIP which worked fine.

A few days later I found the document  on the winkey website which had a very interesting paragraph:-

There have been cases where a WKUSB‐SMT has entered a lock up state due to a nearby lightning strike, a high RFI field, or other very unusual situation. In most cases the WKUSB can be restored to normal operation by pressing and holding the red pushbutton for about six seconds until it responds with an R followed a few seconds later with an OE (dah‐dah‐dah‐dit).

This technique was tried and the WKUSB-SMT recovered. It did reset the EEPROM so all settings had to be re-entered, but the crisis was over!  Pity this information is not in the manual!

Saturday, 15 February 2020

The Langstone Narrowband Transceiver with Pluto and RPI 4

At the RAL TV meeting last year G4EML demonstrated a narrowband transceiver ("Hayling") using a raspberry Pi 4 a 7" LCD screen USB soundcard and an Adalm Pluto. Talking to G8GTZ at the recent Didcot Rally I found that the code has been uploaded to github ("Langstone")so on my return from the rally I decided to try it out.

The first attempt at building the code resulted in a no frequency display on the screen. The log seemed to be objecting to my USB sound card, so I changed it for another one I had and I was getting  the frequency readout but no audio

I then noticed that the display seemed to think I was on transmit. I consulted with G4EML and found that there should have been a pullup resistor on the GPIO PTT input pin. With this modification the display indicated RX and i got receive audio and could hear signals

I took a listen to my transmit signal. The dots sounded fine but i discovered the centre button on a 3 button mouse was needed to send CW, which I didnt have. I got no audio on transmit until I discovered the USB sound card mic input needed a computer headset (electret) microphone rather than my (dynamic) heil headset 

To try it out on the air I hooked up a 3W 1296MHz module and had a nice 2 way qso with a local on the band

I mentioned my findings to G4EML who updated the code to have a key input and a PTT output to drive an amplifier. He also added band output pins to auto switch external amplifiers and preamplifiers

I was then interested  to see how the system would work as a microwave IF. I connected it the radio on 144MHz to my 5760 to 144MHz Transverter and could hear the GB3OHM beacon on 5760.9MHz on a horn antenna. I then realised the pluto works directly on 6cm so I connected it directly to the horn antenna and could hear nothing. I then used the KX3 and the transverter to calibrate the Pluto and found there was a 65kHz offset, on which frequency I could just detect GB3OHM. I dug out a DEMI ATF36077 preamp and put that infront of the Pluto and the beacon became quite readable

All that is needed now to make the rig suitable for portable operation is a panoramic display!

Wednesday, 29 January 2020

CQ160 contest 2020

Having had so much fun in the ARRL 160 contest I returned do the CQ 160 in January from DEMI. To avoid the previous issues with connecting in Charlotte I flew on an American Airlines codeshare flight which was on a BA plane direct from Gatwick to Orlando, arriving early at 1430, Steve and Sandy met me at Orlando and after a fish supper we drove the 3 hours to Live Oak.

The rules for this contest are not quite the same as the classic CQWW rules. Multipliers are US states+VE provinces+countries. Although DX stations (and only DX stations)  send their zone, they dont add to the  multipliers!

The contest started at 1700 local on Friday under the call K0DI. Unfortunately the starting operator was stuck on a plane at the gate in Washington, so I was volunteered to start. Calling CQ for 10 minutes, nothing much happened, then the pileup started, which was a new "run" experience, which I continued for 2.5 hours before switching to mult duties retiring at 2300 I returned at 0600 and operated till the band closed at 0830 working some JA but no VK/ZL

Having not experienced the overnight shift I returned at 2300 to teamup with Steve. I ran , he searched. I ended up running for 8 hours. The band closed around 0800 sunday morning again . We resumed at 1600 that afternoon  after a visit to the club shack and surprisingly had 17 qsos in the last hour

For light entertainment on the monday after the contest we replaced the power supply in a quadra VL1000 amplifier which had been hit by lightening.

Saturday, 14 December 2019

ARRL 160m contest

While attending Microwave update I managed to get an invite to operate the ARRL 160m contest from the Downeastmicrowave site in Florida

I flew from Heathrow on Dec 3 to Orlando via Charlotte, NC. It was to be my first flight on an AA Airbus made plane. Unfortunately it broke so we spent two hours getting it fixed at Heathrow. This resulted in missing the Charlotte connection and being put on the standby list for the next flight. Luckily I was 1st on the standby list and was the only one (of 36 standby) to board. Steve and Sandy met me at Orlando and after supper we drove the 3 hours to Live Oak

The station and antennas were all ready to go, so all i needed was a training session which was easy as we were to use a pair of K3, The available multipliers were ARRL sections (83) and countries. The contest started at 1700 local time I shared the shift to 0300 doing most of the "running", then had a sleep.  The band closes at 1000 and we resumed at 1500. Again I operated till 0200 then sleep. During this period we managed to work the final two sections (NL and ND) needed for a clean sweep of all 83 sections. The contest ended at 1000 local time. The final score was as follows:-

 Band     QSOs     Pts    Sec
   1.8    1314        3201  136                     Score: 435,336

The Transmit Antenna
after the contest i hooked up the 1000' NE beverage to my RSP2PRO to take a listen on 474kHz WSPR. I was surprised to see so much of G0MRF:-

191210 0006   1 -30 -0.19   0.4757844  G0MRF IO91 37           0  5279km
191210 0138   2 -25 -0.23   0.4757845  G0MRF IO91 37       
191210 0208   2 -26 -0.23   0.4757845  G0MRF IO91 37
191210 0216   2 -23 -0.36   0.4757843  G0MRF IO91 37
191210 0232   2 -25 -0.27   0.4757845  G0MRF IO91 37 
191210 0238   1 -28 -0.27   0.4757845  G0MRF IO91 37
191210 0304   3 -23 -0.27   0.4757845  G0MRF IO91 37   
191210 0548   1 -28 -0.53   0.4757846  G0MRF IO91 37
191210 0602   2 -27 -0.53   0.4757845  G0MRF IO91 37   

Thursday, 21 November 2019

9cm Outing to Cleeve Common

Having finished the 9cm  power amplifier integration I decided it was time to try it out on DATV. Noel G8GTZ pointed out that there was to be a UKUWG contest on November 17 for which he would be going out for, so I could combine the two activities. I chose to visit the usual Cleeve Common IO81XW site. Noel did suggest that the site he was going to would be workable from the Radio Mast car park, avoiding the need to cart the gear across the common to the trig point area.

Arriving at the car park at 0930 there was so much fog I could not see across the field but I set up the narrowband system to check out the receive system.

The fog on arrival

GB3ZME and GB3OHM were loud so all seemed to be working. I then worked M0HNA/P, G8CUL, G4LDR and G3VKV. Noel then arrived on site and we worked easily on 9cm narrowband. I then switched to DATV. He saw my 9cm signals easily, however due to issues at his end it took me a long time for me to receive his signal, but I eventually succeeded.

The mobile DATV station
Noel's 9cm DATV signal

After finishing working Noel I eventually managed to attract the attention of G4ODA on ON4KST to try working him. The path didnt look too promising as shown in the following picture:-

With patience e did work on cw at 160km, being my best DX. As I could find noone new to work I left the site and came home. 

I even found time to put in an entry to the contest and was most surprised with the result:-



Thursday, 15 August 2019

A dedicated portable Narrowband/ DATV system for 6cm

Having previously used  parts of my 6cm eme system for portable DATV operation from Titterstone CleeBrown Clee and Cleeve common it was very apparent that the large numbers of interconnecting cables and its lack of waterproofness was a handicap. A dedicated, waterproof system was needed , in the style of the 24 GHz system.

Having not used the Fujitsu amp in the 6cm FMTV system I had an amplifier. I also had a DB6NT preamplifier, however I needed a compact Transverter. The DB6NT mk4 had good performance but cost a lot. I looked around for a second hand one to no avail. In a conversation with G4DDK at Heathrow airport on our way to Frederichshaven we were discussing what we were looking for. He was toying with the idea of a 6cm DB6NT mk4 xverter to upgrade the mk2 in his eme system. I offered to buy his mk2 and this convinced him to go ahead with the plan. Problem solved

Sam shipped the transverter which produced over 200mW (too much for the Fujitsu amp) and could hear the GB3OHM beacon on a patch antenna, time for encapsulation.

I found another waterproof box like the one used on 24 GHz in which the Fujitsu amp just fitted. The Transverter was mounted on a plate on the sidewall of the box, the amplifier was mounted in the base of the box.

To offer some protection and to allow monitoring when masthead mounted a PIC controller was deployed. It monitors  positive and negative volts, current and temperature. It also sequences the antenna change over relay and bias control

Tuesday, 13 August 2019

More 6cm FMTV upgrades

When operating on 6cm FMTV from cleeve common having multiple boxes in the system was a handicap. It meant a lot of cabling had to be changed when swapping bands. What I really needed was to have a display built into the control box, removing the need for an external monitor. Looking on ebayusa I found an unboxed cheap 7" LCD display with the usual selection of HDMI/VGA/Composite inputs that would run off 12V. The quoted dimensions convinced me it would fit in the control box.

When it arrived it worked fine and fitted easily in the control box, as shown below. The controls were mounted on the side of the box. There was still room left in the box; perhaps I can squeeze in the microphone amplifier and audio amplifier so it can have WBFM voice qsos?

Monday, 10 June 2019

24GHz DATV World Record extended

As it was IARU contest weekend and G8GTZ was going to be portable at Dunkerry Beacon IO81FD it seemed an ideal opportunity to extend the 24GHz DATV record from Cleeve Common IO81XW81. It would also nice to try out the upgraded 6GHz FMTV system. so a trip to Cleeve common was setup for the Sunday morning

Friday night I checked out the 24Ghz system and was getting low transmit output on both DATV and SSB. Many hours were spent investigating with no success

Saturday morning I got out the spare 2W W2PED amplifier module. Over coffee I spotted that the replacement amp had 6 bias pots, the installed amp had 5 bias pots. Analysis showed that one of the Bias pots had come off the installed board. The multiturn pot is very small so I had to resort to raiding a 2Ghz amp board to harvest one. It was installed and the bias set to match the voltage on the replacement module. After many lost hours we were good to go

Sunday morning, Arriving on site at 1030 first the FMTV was setup

Noels picture was quickly seen:-

After the 2 way QSO the FMTV gear was then removed and the 24GHz equipment Installed.

 To align the antennas we had a 24GHz narrowband FM QSO, Noels signal pinning the s-meter on the FT817, looked promising. I then transmitted DATV and Noel instantly saw the picture:-

Noel then transmitted and I instantly saw TV data being received but no picture. After Noel trying lots of datarates and parameter permutations a picture was finally seen:-