Tuesday, 15 November 2016

Post Scotex

Back from the Scottish Microwave Round Table. I spoke on the subject of my Anglian 3 transverter.
However, the social aspects of the meeting were what it was all about. This is one of the smaller Round Tables and has a limit of just 50 attendees because of limited space in the Burntisland Communications Museum in which it is held. 
The evening meal was held in the Kingswood hotel, some 1.5 miles from the Museum and around a mile from my hotel. I was able to walk from the hotel to the Kingswood in about 20 minutes in the good company of G3AAF. We were joined by G4BAO on the way back. The excellent company and interesting chat made the cold walk quite bearable!
I have to report that the food was excellent and was extremely well prepared and served.
3/4 of the 'Microwave Band' entertained us after the meal, with some interesting and unusual musical instruments. I am completely unable to remember their names (the instruments, that is) except for the accordion and that was a bit smaller than usual.......I'm sure it has a special name as well.

As for radio since returning, well I have been back on the moon, using digital modulation on 23cm and collaring several more initials (#) for my growing 23cm total. QRA64 was very effective at allowing me to QSO G4BAO off the moon for the first time. Our dishes are just 1.9 and 2.3m diameter.

I've also been preparing to launch the PGA432 preamp kit. This is a low noise, high dynamic range, preamp with effective input filtering and bandpass output filter. Gain is adjustable and powering over coax is an option. I will announce on my web page when the kits are ready for sale.

73 de Sam

Tuesday, 25 October 2016

Anglian update

Sales of the Anglian 3 144MHz transverter have been going well. I have mainly been limiting sales to the UK and Europe whilst I clear my backlog of orders.
Many of my customers have been buying the 8W PA short kit as well as the transverter.
For now I am able to hold the price of the Anglian 3 to £120 but after the noticeable increase in the cost of parts for the transverter I will have to increase the price in the New Year. The increase is mainly due to many of the parts being sourced outside the UK and priced in USD which is approximately 20% higher against the GBP than before the Referendum result caused the GBP to slide to a more realistic value. 
I will take kits to the GM Microwave Round Table next month, where I will be giving a talk on the Anglian. I also plan to take kits to the Heelweg (Dutch) meeting in January. The ferry trip is already paid for!


So how did the SDRPlay, play?

I've now got the SDRPlay connected to the Lenovo notebook and the 13cm transverter 2nd IF output. Switching the transverter LO to give 2300MHz coverage and tuning the SDRPlay to 164.830MHz I can copy several 2320MHz beacons and the local one at Martlesham, although very strong, does not cause any discernible strong signal problems. This is reverse operation of the system.
I will use it as a more conventional parallel 2300MHz receiver this evening during the UKAC/NAC 13cm and up when the main system is on 2320MHz. It should be an interesting test.
200W out to a 67 element yagi.


Sunday, 23 October 2016

Back to the SDRPlay

Today I bought one of the cheap Tesco Lenova notebook computers to use with my SDRPlay and other ham radio programs. At just £129 the notebook is good value. I was alerted to it by G4HUP and although my local store was showing 'out of stock', when they checked they found they did indeed have just one left in stock.

I downloaded antivirus software as my first programme and then downloaded the SDRPlay application together with SDRUno.

I'd already played with SDRUno previously but found it rather awkward to use and this time was no different. It really does need another GUI.  The existing one is not at all well designed. It does have some nice features that are not available in HDSDR, but I am much more familiar with that application. Maybe if I persevered with SDRUno............ 

However, after downloading the EXTIO dll, I was ready to fire up the new notebook and SDRPlay. Connected to the DG8 masthead preamp and tuned to the various beacons on 2m in turn, it acquitted itself quite well. I knew it was working on the correct frequency and had a reasonable noise figure (quoted as about 4.5dB).

My intention is to use it, tuned to 128MHz, on the second IF output of the 13cm transverter's receive converter to listen to 2304MHz EME signals after transmitting to the moon, from the UK, on 2320MHz. Alternatively it could be used tuned to 148MHz whilst the transmission is on 2300MHz. All of this is with my homebrew 13cm transverter, which although it has switchable LO frequencies for the 4 principle 13cm EME sub bands, it does not have remote switching for them, which makes it awkward to use from the operating position on the other side of the shack. Since selling the FT847 several years ago I have lost the ability to easily switch between listening on the two different allocations.The FT847 is one of the only rigs I know that has reasonable SSB receive performance at 128MHz for this type of crossband operation.

73 de Sam

Tuesday, 4 October 2016

Update to the Anglian 3

I have made a small update to the transmit path of the Anglian 3 transverter.
All subsequent kits will contain the new parts and those that have already gone out will be offered the alternative parts.
The update improves the transmit path gain, which gurned out to be a few dB low of what it should have been.
Slightly more IF drive was required to reach full output in the no-IF amplifier version.
More kits will be available after I get the RSGB Convention talk out of the way!!

Monday, 3 October 2016

RSGB Convention

Nearly completed my slides for my talk at the Convention 'The secret life of the transverter'.
My talk is about the principles of the transverter, interfacing it to an HF rig, and some things to look for in the transverter system. I have deliberately focused on the IC7300 interfacing as a result of recent interest in this particular rig as a transverter driver.
I understand that M1BXF has acquired an IC7300 for use in the Convention HF station. If you have wondered about this rig as your next venture in SDR technology, here is your chance go come and see one in action, and maybe go hands-on with one. Then come and listen to my talk!
I am not deliberately talking about VHF transverters (my recent speciality) but rather in more general terms about the subject.

Sunday, 25 September 2016

A break

I'm taking a short break from kitting Anglian 3 transverters. Two weeks of intensive kitting, component preparation, paperwork and shipping has taken its toll. I need a break from it. 
Started to investigate integrating the DRiACS dish controller into my existing system, beginning with an eddy current damped gravity pendalum elevation indicator. 
I was extremely disappointed with the Machine-DRO digital pendalum inclinometer. Although the reading updates very quickly ( too quickly?) it is very unstable. It seems to be similar to the well-know 'Lidl' digital inclinometer. That is also totally unsuited to moon tracking as it takes ages to settle down to a reading. The Machine-DRO is exactly the same. It is suitable for indicating elevation if hou have time (>30-45seconds) but totally unsuited to tracking, where the 'noise' masks the immediate moon (or sun) position.
So, i'm back to trying to implement the MAB25 absolute encoder solution, but with the possibility of using eddy current damping to reduce reading instability, especially during windy conditions when the dish mount will inevitably shake.
On a very positive note, the add-on GPS clock works well, even inside my garage shack. GPS lock is solid. The DRIACS indicates the actual moon ( or other celectrial object in the almanack) without worrying about clock drift.