SSB adapter, converter to suit Collins R390A receiver.

[onlineguy]

Has anyone an ssb adapter to go with a Collins r390 receiver ?

Anyone know anyone that may have one ? Collins, TMC cv591, hammarlund etc.

Been looking a while but no luck as yet.

I posted this ask last week possibly on the wrong thread.

Admin could you delete the other request on the parts wanted thread please. Many thanks.

73 all. Thank you. Andrew.

[Aub]

Doesn't an SSB adapter normally go with an AM transmitter? The receiver just needs a BFO doesn't it?

Cheers

Aub

[Outposter30]

Originally Posted by onlineguy

Has anyone an ssb adapter to go with a Collins r390 receiver ?

Anyone know anyone that may have one ? Collins, TMC cv591, hammarlund etc.

Been looking a while but no luck as yet.

I posted this ask last week possibly on the wrong thread.

Admin could you delete the other request on the parts wanted thread please. Many thanks.

73 all. Thank you. Andrew.

Try this link:

http://www.treetopcircuits.com/pmwik.../Main/Products

[Radio Wrangler]

These things usually take an IF signal from late in the final IF. Onlt then does the signal get exported to the adaptor and meet a proper SSB-bandwidth filter. The Base receiver is set up with its AM filter operating.

Thus the frequency space of the unwnted sideband goes right through the base receiver and can use-up its dynamic range and dominate AGC action if it contains any signals larger than is in the sideband that gets chosen later in the adaptor.

Consequently even a very good AM set with an SSB adaptor is easily out-performed by a receiver with an SSB filter positioned early in its gain profile.

As a result, the professional users with the money to pay for an R390 in the first place, did not buy many SSB adaptors, they shifted over to receivers designed for SSB from the outset. That's why SSB adaptors are fairly hard to find. Military comms went more for RTTY than for SSB in the period. R390s and RA17s did have filters for this service and the late IF outputs suited it.

They do work, but in difficult circumstances they can be found somewhat disappointing.

David

[John KC0G]

There is lots of history here: http://www.navy-radio.com/rcvr-ssb.htm

73 John

[Aub]

I must be getting my wires crossed here. The only time I've previously seen mention of an SSB adapter was for use with a Heathkit DX100U AM transmitter.

Aub

[turretslug]

Some of the outboard SSB demodulators made for legacy military/professional receivers were extraordinary devices, large, expensive and sometimes rivalling the host receiver complexity and featuring sophisticated IF and AF filtering and ALC, tracking AFC and so on. It was one thing to be a keen amateur or SWL and carefully juggle RF gain, AF gain, main tuning and BFO with an envelope-detector receiver to make SSB reasonably intelligible for a few minutes at a time, another for an "oppo" to be able to depend on immediately being able to tune and read a faint and ephemeral SSB signal that might be of life-or-death nature under trying conditions, then be confident that after hours of no activity, the next reception would be instantly on-the-nose with nothing missed. Hence "couldn't they just have used a 6BE6?"-type objections from someone seeing an electronics-stuffed 19" rack! There was more to it than that....

[onlineguy]

Thanks to Radio Wrangler, and Turret slug , Aub, they answered you're question way better than I could.

Thanks to both and thanks for link to John and Outposter. And anyone I have missed. Andrew.

[onlineguy]

The Collins R390 when used in SSB , bfo switched in, is somewhat raucus when one turns up the rf gain.. agc action etc comes into play and I find I have to ride the rf gain .. . I have used an ssb converter with the set several years back and one could keep the rf gain up and receive perfect audio in ssb .

Anyway just another toy to play with I suppose!

Iv tried the solid state and ic ssb converter jobs out there...little black boxes..not keen, besides Iv got an aversion to plastic. Valves and analogue that's me.

I swapped on my tmc cv 591 converter . I have the 390 here but no ssb converter.

Thanks for help and advice. 73.

[G3VKM_Roger]

Originally Posted by Aub

I must be getting my wires crossed here. The only time I've previously seen mention of an SSB adapter was for use with a Heathkit DX100U AM transmitter.

Aub

The SB-10U, if I'm not mistaken?

73

Roger

[Aub]

Thanks for the info. There's clearly a lot more to them than I knew.

I don't know any model numbers, but i believe there was something similar for the KW AM transmitters.

All the best

Aub

[QQVO6/40]

Greetings all.
Hello Andrew.
The sideband converter that was originally intended for use with the R-390 and R-390A was the CV-157.
All valve and it used, I think, 43 valves and mostly double triodes.
Quite a heavy beast.
David is correct in that it took it's input from the IF of the receiver. Motor driven automatic tuning within the 15kc bandwidth of the receiver.
It is a true sideband splitter in that for the same radio transmission you could have voice on one sideband and teletype on the other sideband. Or any combinations of voice and teletype.
I have one stored here I restored some years ago. Quite fascinating to watch the front panel indicator coping with the vagaries of sideband transmissions from overseas.I have the full setup of R-390A, CV-157, HAL ST-6000 terminal unit and Teletype printer plus ancillary loop power supply.
I have not used it for some years as I haven't got the room to set it up. Lots of other projects and just not enough time.
Cheers all.
The Navy Radio site mentioned by John is quite good.

[QQVO6/40]

Hello Roger.
The Heathkit SB-10 was indeed a sideband adapter but for use with the Heathkit "Apache" AM transmitter.
When SSB was new last century Heathkit made this adapter to go with their AM transmitter as a low cost option to get into SSB for radio amateurs.
The SB-10 used the RF output from the AM transmitter and use phase generation to create an SSB signal of max 10 watts output on the old pre-WARC bands. The SB-10 made use of the power supply of the Apache transmitter for all of it's needs.
The SB-10 has 9 valves in it.
I have one here but I have never used it as I do not have the Apache transmitter to accompany it.

Ahhh the good old days!
Maybe not?
Good to look back on and remember when.

Cheers all.
Robert.

[Radio Wrangler]

The basic AM/CEW sets like the AR88 and HRO simply jammed a strong BFO signal into the AM detector to receive CW. The same diode also did the AGC, so the set thought there was a walloping great signal and the AGC backed the gain off a lot. CW operators had to select AGC off and drive the RF gain control manually.

Using one of these sets on SSB meant doing the same thing, as well as accepting an imprecise BFO and an overly-wide IF filter. You could do it, but it was messy and noisy.

Later generation sets put in a separate AGC detector and got around that problem. But even if they had a crystal oscillator for the carrier frequency, they lacked the much more expensive narrow IF filter. The R390 and RA17/117 fit into this category. To make a bette job of SSB reception, rather complicated units were made which took a signal from as early as possible in the final IF, had specialised upper and lower sideband filters and a precise carrier oscillator (in some cases synthesised from the main receiver's master oscillator) These beasties really would sit on the right frequency (with the optional synthesised LO adaptor box) and they did have the right filter bandwidths and separate AGC.

Racal, when they transistorised their Wadley receivers to make the RA1217 went so far as to dump their 100kHz IF LC filters and fit crystal filter units for AM, USB. LSB. RTTY and CW to the purchaser's choice.

The Racal Wadley structure, however had a lot too much wideband hardware ahead of their narrow IF filters and they are rather prone to overload. The R390 with its simpler arrangement is not so bad in this respect, but it was still used in P R Rafuse's (MIT) paper in 1968 on a new mixer with better dynamic range - as a comparison example to show how far ahead the new mixer was of a respected receiver.

Racal realised they were a long way off the peak of the game, so they took out a licence for the Rafuse mixer and designed their RA1772 around it. They took care over dynamic range and third-order intermods and produced a very well respected receiver for the newer and more demanding conditions on HF.

Collins already had filters nearer the antenna, but their mixers were rather basic in performance. They eventually met strong competition from Watkins Johnson.

Anyway, an owner of a classic R390 or RA17 may feel that the matching SSB adaptors complete their station and look great together, they were a bit of a backwater, and soon receivers designed around SSB came along which were a lot less clunky to operate. But times were changing in other ways. The importance of minimising non-linearities in the earlier stages of a receiver was being discovered around the same time. So it's fair to warn that even the most complex SSB adaptors can be somewhat disappointing. A lot better than the bare set, but overshadowed by what came after.

David

[ms660]

I had a Racal independent sideband unit, £5 I think it was.

The BFO injection in the AR88 etc wasn't that large.

One of my Hallicrafters had a BFO variable amplitude control.

Always wanted a Collins but never got round to it.

Lawrence.

[dave walsh]

I'm genuinely surprised to read the information on this thread. I didn't realise that BFO injection was so complex in the early days [until later, smaller, options appeared] even though I understood [at least] a little about the process. I'd never read anything about all this before. A Hammarlund Super Pro is currently on offer without the PSU here [which, apparently, weighs almost as much as the receiver itself] but a 43 valve BFO competing with the set weigh wise [post 12*] is a new one on me!

Dave W

[QQVO6/40]

Greetings all.
CV-157.
I was in error a little bit. It has 44 valves and not 43 as I had previously quoted.
More tidbits.
It weighs 104 lbs in all of it's nakedness.
Accepts an IF frequency of 450 to 510kc and then down converts that to 100kc to work it's magic.
The heterodyne oscillator operates 100kc above the incoming frequency.
Consumes 250W of mains power.
David is correct in saying that there are a lot of smaller devices around that appeared not long after these large chunks were put into service.
It is not really of much use today as my small rice box will pull ssb signals out of the mud very well and not be a back breaker to get there. The only thing a rice box can't do is to run same frequency diversity. But let's be honest here; who in the amateur radio world runs voice and telex on the two sidebands of the same frequency. I can't think of any.
I did it once with an old friend years ago to see how it would work and it did do very well. He is now a silent key and all of his gear has gone.
I just got it going to say yes I have one and it was fun to play with and now time to move on.
All good.
Cheers all.
Robert.

[Radio Wrangler]

Rather a lot of the valves in the fancy converters are there to do AFC, which relies on a vestige of carrier being transmitted. Again, no real benefit on the amateur bands.

If you want same-frequency diversity, buy two rice boxes! and together they'll still be lighter and smaller.

There are some interesting assumptions that have embedded themselves in folklore and become accepted 'truth' - I have an Icom IC7700 in the shaxk. So some people keep warning me it's no good for contests having only a single receiver. Hmm, so what's that R9000 thing I pair it with when I need a second receiver? Some people warn me the PA transistors blow up. Yup, they do when someone doesn't know it's programmed only to work with PIN switched linears. I don't use a linear, so no risk.

[onlineguy]

Qqv06/40

Thanks for such an informative letter . The finer points of ssb converters I'm a bit rusty on so I'm happy to be the catylst for all the replies and education here and folks communicating with one another. , ****** marvellous! I watched a chap on you tube using what looked like a Collins ssb converter, possibly the CV157 you mention , it was bigger than the Collins 390A he had it hooked up to, another in New Zealand, same set up, can be seen. I almost had one sorted from a chap in Ireland few years back but there was a problem with shipping and It meant I would have had to travel over , take the ferry . Decided against it .

Anyway , pleasure to have "met" you here. All the best. Andrew.

[onlineguy]

Radio Wrangler, thanks for the education. Always good to see your posts. Informative and in depth. Cheers. Andrew.