Forgot your password?
fv1609, February 4, 2009 in British Radio Equipment
New here, but been M3KXZ for good few years now. Active on HF using CW (very occasionally SSB), always portable somewhere. Getting better and better. Still wanting to upgrade but with working about 7 days a week, and family..... never enough time!
I've just passed both my Foundation and Intermediate exams back to back this afternoon. :-D
Congratulations!!! Started foundation recently with Ian K. from EMLRA.
M6KBO I run a VCR321 and VCR353 Clansman out of my FV432.
M6PFA working a Clansman 320
G6WZL, not been on air for a while!
I’m afraid this is going to be a long one!
It is 50 years to the day that I received my Amateur Radio (Sound) Licence B.
What disappointed me at the time was the snottiness of holders of Class A Licences who regarded the Class B Licence as a novice licence. Well as a schoolboy I passed exactly the same City & Guilds of London Institute Radio Amateurs Exam (RAE) as the holders of a Class A Licence. So our technical knowledge was required to be the same. I was not aware of any classes to teach you how to become a radio amateur, so I was self-taught from reading books & building equipment.
What I hadn’t got was the Morse Test, I just wasn’t up to the required speed (12 wpm). But once a licence became available that didn’t require the Morse Test I jumped at it. Although since 1950 there had been a dodge to apply for an Amateur Radio (Television) Licence that just required the RAE & no Morse Test.
The TV licensee enjoyed the status of a call sign in the G3 series suffixed with /T. Transmissions were restricted to UHF & above for television (& sound in connection with those tests). If the licensee passed the Morse Test the /T could be omitted for those communications not using TV. Later all TV licensees (including Class A & B) were issued with call signs to be used for these transmissions in the G6AAA/T series.
Although I did later set myself up to receive amateur TV I had no interest in transmitting it. My first target was to get operational of the 420 – 460 Mc/s band (70 cm)
In 1964 there were no transistors available that could work as high as 420 Mc/s. You either had to build a converter that simply went into a crystal mixer or the equivalent thing that in my case a naval P58 radar receiver. Very insensitive! I had to build a two-stage preamp using CV354 disc seal triodes.
The step forward was to get hold of a “BBC 2 tuner” & bend it into the amateur band. The transmitter started with an 8 Mc/s crystal multiplied up to 432 Mc/s with QQVO6-40A in the PA.
I would have been delighted to have discussed on 70 cm my so called “novice” licence with any holder of a “full” licence had they been capable of getting onto the band.
I had my first article published in 1966 for Practical Wireless.
Then moved from Devon to Bristol.
As can be seen by the corner reflector I had just built, SHF & above was generally primitive in the amateur world. Forays onto 9 cm & 5 cm were with klystrons in polarplexers using circular wave guide feeding a dish. For 9 cm a beer can worked well & for 5 cm a Brasso tin. Provided the other station used the same I.F. (usually 30 or 100 MHz) you had true duplex with one station transmitting vertical polarisation & the other horizontal. A little coupling from the transmitting klystron gave the local oscillator injection for the receiver.
For 3 cm waveguide (WG16) did crop up in scrap radar equipment. Klystrons with internal & external cavities were not too difficult to find. For 1.5 cm (21 GHz) there was nothing around surplus but a diode could be forced to double from a klystron bent to 10.5 GHz & produce some tiny levels of power in microwatts but gave results as dish gains were significant at these frequencies.
(IARU Region 1 = Europe, Africa, Middle East and Northern Asia)
21 GHz was 1,000 Megs wide, sadly that disappeared. To be replaced by a very restricted allocation in 24 GHz. You had to get a permit for a location, specify your exact frequency & with whom you are going to contact & think the times you were going to operate. Something very strange went on in that band I think. But it’s funny how all these old pretty useless bits of the spectrum have proved to be so important these days!
Solid state Gunn oscillators for 10GHz became easy to obtain & lent themselves to portable operation as they no longer required peculiar high voltage power supplies for klystrons. But this was wide-band FM with drift & no precise frequency determination.
The breakthrough for me was to build a solid state 5 watt transmitter for 1152 MHz. This was a magic number when used in conjunction with varactor diodes allowing access to all the microwave bands available at the time:
1,152 x 2 = 2,304 MHz (13cm)
1,152 x 3 = 3,456 MHz (9cm)
1,152 x 5 = 5,760 MHz (5cm)
1,152 x 9 = 10,368 MHz (3cm)
1,152 x 21 = 24,192 MHz
The above were NBFM (or CW) but as a bonus 1,152 + 144 = 1,296 MHz (23cm SSB)
This allowed much more compact & safer equipment that lent itself to portable operation. Of course the established rationale was “line of sight” for microwaves. So we operated from hills & mountains, with South Wales providing some of the latter for me. Height was important between stations to clear intervening obstructions but also to allow extra height for the curvature of the earth. One was restricted to sunny day operating with a dish on a tripod & jolly good fun it was.
But if it rained the equipment got wet & we all know how rain scatters microwaves (as in weather radar). So I looked for a more robust way of operating. This is when the military vehicles started for me. I purchased an FFR Lightweight from Brian Bashall (Dunsfold) & built in it a permanent 10 GHz solid state SSB set up. Yes & even still I would get the odd “novice licence” dig from “full” licensees. My comment would be yes let’s talk about how much of a novice I am on 10 GHz SSB (this was in an era when activity was predominantly still WBFM on Gunn oscillators).
In those days microwave dishes were hard to get, there was no satellite TV (oh that’s where some of our spectrum went!) I used a battlefield dish but mounted it in a more delicate frame, I fixed this on a Decca radar scanner base & bolted into onto the roof. It was rotated by a windscreen wiper motor, I controlled this with a pulsed model railway controller so that I could turn the dish at a few rpm to a fraction of degree per second.
The rotary waveguide joint fed into a waveguide relay that fed the RX or TX. The round black thing was a Magnesyn compass sensor that fed a display unit above the windscreen with a 400 Hz power unit.
The dashboard housed a Desyn display from a radio compass in this instance fed from a Desyn sensor in the radar dish base. The reading from the Magnesyn compass gave my bearing which I then fed to the outer scale of the dish direction display, I corrected it for Grid North & thus had a complete display that would match my OS map.
The transverter was built largely within the waveguide & the I.F. was 144 MHz from a FT290R.
I could be operational wherever I travelled in a matter of moments, by simply raising the dish & setting the elevation to the horizon. This lent itself well to spontaneous & non-intrusive operation from beauty spots where a mast or tripod would be prohibited. Plus the appearance of the vehicle suggesting I was perhaps fulfilling some official role.
Although I felt I had a rugged installation & could go anywhere in any conditions, for success one must have someone to communicate with. But nobody had kitted themselves up in a similar way. So much of my effort was wasted.
Where I lived near Winchester was a poor location to operate from, but I found that I lay under a 10 GHz path used regularly by Oxford University to Hayling Island (sea level not “good” for microwaves). This made me realise I need not go out portable on a hill top again!
I did pass the Morse Test & took out a Class A Licence. Not for HF but to assist in DX working on 10 GHz troposcatter.
I moved house to an even worse location. Worse not due to height, surprisingly that is not too important, the requirement was a reasonable run at the horizon to get to the disturbances in the troposphere. But of course whilst it rained you could work from anywhere!
So apart from a cross-over period in the 1970s, the attraction MVs has had a detrimental effect on my amateur radio. I now have a large pile of waveguide, klystrons, travelling wave tubes, mixers, slotted lines, wavemeters, power meters etc. I must thin these out so any enquiries are welcome.
Sorry it has got rather long but the 50 years on the air (& we won’t talk about the bit before that) just kept coming!
That's a heck of a lot of operating and recognition - nicely done
Something of a black box opeator here, and I still have my old FT-290R mk1, although I'm not at all sure it works anymore - haven't used it in close to a decade; I have to replace the mike cable at some point too, but as I've got an FT-817ND, that task's taken something of a back seat - especially with the acquisition of a PRC-320 recently!
Congratulations on the 50 years and interesting to hear of the early days of UK microwaves - I worked closely with some of the newer generation of operators (G4DDK, G4FRE, G3XDY etc) at Martlesham in the 80s and 90s. My own route into military vehicles was rather similar having bought first the NCRS trailer as a shack and then the SUMB as a self propelled field day station (having got fed up with putting up tents and masts for the weekend!)
73 de G0OZS
Thank you Roger. The FT290R is a useful little thing for home or portable. I really only used it as an IF for the transverters, but it was a very useful building block. Yes a black box, once it was argued that a true amateur would have built a compact transceiver, but I would sooner use an integrated circuit than built up the equivalent thing with dozens of transistors! You have to use these building blocks to get them to do what particular project that interests you.
Amateurs love to adapt things & a lot of my earlier stuff was based on scrap radar equipment & old GPO links. I think my first 13cm rig was based on the first microwave link to the Isle of Wight. Early narrow band PCB oscillator driver boards were based "balloon boards" ie the transmitters contained in met balloons. I understand now that certain satellite TV amplifiers can be tweaked into low power PAs.
Going back to the FT290R I still have mine but it has not been turned on for 30 years! I believe there is a charging process to be used to help reform the electrolytics so they don't pop.
Iain, yes Martlesham was focus of a lot of early amateur microwave activity as well as the professional role! Yes a comms vehicle is the way to go. I have a 1 Ton Cipher Office that would be ideal for that sort of thing, if I turned my mind to it.
I understand that there there is really no home brew on 3 cm. Apparently there is a solid state transverter module made in Germany costing several £K that is widely used. delivering 1 watt & this is high power when you remember klystrons & Gunns gave 5-10 milliwatts.
Makes my TWTs & hombrew stuff seem primitive. I have given the transverters away to perhaps the only remaining homebrewer on these bands & I understand they are still giving service. I still have the TWTS & PSUs. Here is the set up I had in my loft.
This was remotely operated from my shack which was some distance from the mast & rather small. I just fed in 28 MHz & remotely selected the band I wanted to operate on. The only task was to change the feed in the dish.
10 GHz set up
5.7 GHz set up
2.3 & 3.4 GHz set up switched to the same TWT
Note the 15mm pipe on the right is not part of my set up! Although in Bristol I used 22mm water pipe as circular waveguide that I fitted inside the mast.
The Martlesham Microwave Round Tables are still going - now in April rather than foggy November - as a club we still run beacons on all the higher bands at the top of the radio tower. There are a lot of stations using the DB6NT modules - originally they were his homebrew designs but he has now made a successful business from manufactured units. There are still quite a few kit transverters around using MMIC amplifiers - in fact Sam G4DDK has also done VHF and UHF variants as kits recently - and many people have adapted Satellite TV receive chains and cellular base station transmit parts to work on various microwave bands so the spirit of creative reuse is still there.
I have fond memories of an FT-290 in my early days on air - now long replaced with an 817. The photos remind me of the equipment used in the early days of G4MRS/P in VHF field day - I used to operate the night shift on 70CM using a station built by G4FSG (now RSGB Chairman) to a design by K2RIW and worked well into Eastern Europe on a good day. I think the last big thing I built was the PSU and tone decoder for GB3PO Mk III (1989 version) - these days my close vision isnt good enough and trucks are easier to work on ..
A lot of people still use TWT amplifiers at 15-25W on the microwave bands - I think mostly ex satcomms use.
Iain glad the Round Tables are still going strong. I never went to the Martlesham ones just the ones at IBA Crawley Court.
Yes G4DDK rings a bell. I dropped out of this 30 years ago the leading light in those days was G3BNL Cheltenham (so you can guess where he worked) he developed the 1152 magic number concept for multiplying up. But in time it was best to build a transverter separately for each band rather than a single driver. Rather like a power drill it is better to have a separate, hedge trimmer, jigsaw etc rather than keep fiddling with attachments all the time.
Although I could get TWTs that came out of service after so many hours link use, they required large external mounts. The breakthrough for me was getting hold of some Litton TWTs compact & with N terminations they were quite wide band. In fact I still have them & the PSUs. But they were only 1-2 watts.
In my tropo era it was G3YGF at Oxford University & G3JVL at Hayling Island that led the way & I happened to be under their path. At that stage I was given a GASFET preamp which was quite something in those days. There was a student at the time G8NDJ who really threw himself into construction & a couple of years ago I gave him the more usable parts of my gear, which I believe still works.
But he is now very good at spotting bargains for the right bits of sat stuff that can be modified. I've really got left behind by it all, but although my accounts might seem a bit self indulgent it might illustrate how things have gone from being confronted by "they can't make transistors that work on 70 cm" :-D
Just found a photo I didn't know I had. This is a view of the operating part of the shack 30 years ago. The rest of the shack was the work bench & lathe - so essential for microwave items.
All the microwave stuff was in the loft remotely operated from down here. I had no HF antenna & the HF rig was solely used as the I.F. on 28 MHz which extra filters to give me a nice selection of bandwidths. The 2m rig was transverted to 70cm & 23cm in the shack.
I cold bloody cry. I really could.
I just moved home, and was trying to find the box with the older radio kit (incl the 290) that I'd packed - and the damn things gone walkies Not the only thing either; a box of clothes, a box of books (thankfully nothing irreplacable), and bizzarly, spare kitchen stuff. Had a word with the removals people, they can't find it in their 'misplaced boxes' store either. Just bloody glad my other (more frequently used) radio kit was shifted my yours truly the day before the move!
Just peeved about the 290, not to mention all the patch leads, gash coax, et al. Irritating is not the word :mad:
At least the PRC-320, ID-51A, VX-5R, and FT-817ND (have you noticed the size/portability trend there? ), plus PSU /tuner and a few other odds and sods are all safely accounted for! :-D
Roger that is tough. One would have thought that they would count into the van so many tea chests & count out the same number on delivery.
I think when I next have to do this, I will take a photo of the items going into each box as an aide memoire as to where I packed what & also as some sort of evidence that those things that were packed should still be there at the point of delivery.
By 290 I imagine you mean FT290, so that must over 30 years old. So maybe there are some cheap ones floating around still?
FT290s are almost collectible now - I sold one (original model not R II) for £70 a couple of years back.
KF5DRO, General class license. Located in south Texas. Both my wife and I are licensed. My reason for getting a license was to have working radios in my jeep. My wife saw my magazines and became interested. She is more active than I am. I work the 2 meter band mostly but rarely use the 6 meter band. I have two RT 524 radios and a Clansman PRC 320 HF rig.
G7KNS in Kent. Interested in WW2 kit onwards. Also active on the NRN for those who know what it is.
Following earlier remarks I hate to announce that my FT290 Mk1 is still in regular use in the shack and has the mutek front end fitted.
Welcome Gordon. Glad the FT290 is going strong, it was a very useful building block. Not turned mine on for 30+ years. I suppose the thing to do is power it up at a very low voltage & gradually increase this over a few hours? Sorry no idea what NRN means.
Welcome John sorry nobody has replied to you but as you will see this thread goes in fits & starts. Yes there are quite a few licensed couples although my XYL has no interest in RF or anything green.
M0XXY, Primarily on 4m, where you might guess was where Fire Engine communications lived until the switch to Airwave.
G7KNS in Kent. Can do anything up to 70cms but most likely to be on the local 2m chat channel or 60m both amateur and NRN. In the process of getting a Ferret so I guess 4m mobile might happen via a 352.
You can post now and register later.
If you have an account, sign in now to post with your account.
Pasted as rich text. Paste as plain text instead
Only 75 emoji are allowed.
Your link has been automatically embedded. Display as a link instead
Your previous content has been restored. Clear editor
You cannot paste images directly. Upload or insert images from URL.
Started September 22, 2012
Started May 29, 2011
Started January 2, 2017
Started Sunday at 06:35 PM
Started May 18