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Old 22nd May 2022, 4:39 pm   #1
Ben Humphrys
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Default Restoration of vintage Triplett 1632 signal generator

Hello all,

I’ve been bitten by the 'Ancient Radio' bug, I'm afraid.

My wife Sandra & I made a pilgrimage to the BVWS Golborne swap meeting in March, to see what goes on. We had a smashing day. We met many YouTube celebrities in person after having previously watched hours and hours of their inspiring videos.

Anyway, Sandra must have enjoyed it too, because I popped out to the Gents, and on return Sandra had bought 5 sets including a Sky Queen valve portable, some Bakelite-cased thermionic sets and two 1930s wooden affairs, a Philips set, and one Defiant MSH936 definitely inter-war. Total cost £9:00 so Sandra was really pleased with herself. However if I had any hair I'd be tearing it out. I've already spent £10, just on woodworm killer.

I also picked up a scope and a vintage Triplett AM/FM test generator from Chris, YouTube alias: “All the gear, No idea”, for which both I am grateful beyond words.

So many questions for you guys….

This Triplett 1632 sig generator turns out to be a military set from around WW2 and probably needs restoration itself, even before it can even be used. One significant hurdle with the set is likely to be the output connector. I thought, on first sight, that it was a ‘standard’ female UHF bulkhead-mounted connector, but on inspection the centre pin was solid because it was filled with solder so it's only just male, almost flush. The connector thread diameter is also lower.

It seems that there would have been in-line signal conditioning can containing a signal conditioning unit which would be connected to the output socket via a flying coax lead. This particular instrument doesn't have one.

Can anybody please tell me what it is? Otherwise I will need to substitute it unsympathetically for a UHF connector.

I forgot to take a picture before removing it, but here is a picture of the connector after removal.

Thanks!

Ben
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Old 22nd May 2022, 5:05 pm   #2
Dickie
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Default Re: Restoration of vintage Triplett 1632 AM/ FM signal generator

From 1940, according to the manual. I haven't read it but you might find what you need here.
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Old 22nd May 2022, 5:16 pm   #3
paulsherwin
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Default Re: Restoration of vintage Triplett 1632 AM/ FM signal generator

Quite a sophisticated unit for 1940!
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Old 22nd May 2022, 5:24 pm   #4
Dickie
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Default Re: Restoration of vintage Triplett 1632 AM/ FM signal generator

Unless I've missed something, it doesn't do FM which would be a bit advanced for 1940.
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Old 22nd May 2022, 5:47 pm   #5
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Default Re: Restoration of vintage Triplett 1632 AM/ FM signal generator

Yes, you're right. It seems to just do VHF AM. Still useful though.
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Old 22nd May 2022, 6:28 pm   #6
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Default Re: Restoration of vintage Triplett 1632 AM/ FM signal generator

I used to have one of these, passed on to another member some time ago. It's not military, just 1940s American styling. It should have a termination/dummy aerial, shown bottom right in the circuit diagram, with one of those old fashioned microphone type connectors. Watch out for the wax mains suppression capacitors, mine developed leaks (you know it's 110V mains and needs an autotransformer)
You could replace it with a UHF or N connector with a 75 ohm load resistor and an isolating capacitor. If you're lucky it might have a crystal in the calibrator.
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Old 22nd May 2022, 7:53 pm   #7
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Default Re:Restoration of vintage Triplett 1632 AM/ FM signal generator.

Thanks all of you. Yes of course it's AM only. I need to get a wobbulator, don't I?

I'll try to follow Bill's advice.

Ben

Thanks everyone for your excellent advice. Of course VHF didn't mean FM in those days, did it? How silly of me.

I suppose I need to get hold of a wobbulator for FM work. But there's no rush, plenty to do on the broadcast bands for now.

I will try to follow Bill's good advice, and restore the Triplett as sympathetically as possible.

Ben
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Old 23rd May 2022, 7:32 am   #8
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Default Re: Restoration of vintage Triplett 1632 AM/ FM signal generator

I have one off these in the 2 do pile the connectors is a switchcraft 2501f connector
https://www.tti.com/content/ttiinc/e...=1&customerId=
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Old 23rd May 2022, 9:31 am   #9
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Default Re: Restoration of vintage Triplett 1632 AM/ FM signal generator

Thank you so much FIXITNOW. I suppose I'm enabled to .. well... fix it, now. I will source a Switchcraft 2501F, and lash up a home-made 70 ohm termination case myself.

That link of yours takes me to the Switchcraft website and there's a list of stockists and even the technical drawing of the connector.

The 2501F is in stock at several USA distributors. Postage is so expensive, do people ever club together to reduce P & P costs?
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Old 23rd May 2022, 11:18 am   #10
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Default Re: Restoration of vintage Triplett 1632 AM/ FM signal generator

Quote:
Originally Posted by Ben Humphrys View Post
Thank you so much FIXITNOW. I suppose I'm enabled to .. well... fix it, now. I will source a Switchcraft 2501F, and lash up a home-made 70 ohm termination case myself.

That link of yours takes me to the Switchcraft website and there's a list of stockists and even the technical drawing of the connector.

The 2501F is in stock at several USA distributors. Postage is so expensive, do people ever club together to reduce P & P costs?
i was lucky when i last brought as the company i was at had a Digi key account so were happy to add on the end (saved me all the postage)but they are on eBay it seems

and on odd times you may find a few second-hand ones at a local radio rally if you do them

https://www.ebay.co.uk/itm/152977120...8AAOSw0UdXrH8T
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Old 27th May 2022, 1:00 pm   #11
Kevin Hoyland
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Default Re: Restoration of vintage Triplett 1632 AM/ FM signal generator

Hello this is the set up for it. It is a well made Signal Generator but i have to say if it is made in the USA it will be outstanding.

Kevin.
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Old 27th May 2022, 1:48 pm   #12
Kevin Hoyland
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Default Re: Restoration of vintage Triplett 1632 AM/ FM signal generator

More Photos.
Kevin.
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Old 28th May 2022, 8:57 am   #13
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Default Re: Restoration of vintage Triplett 1632 signal generator

Morning.
You can see in the photos that the 1632 has copper plate shielding and lots of it .
You will see from the photos that i have 2 of them one is 110 volts the other has a 240 volts transformer fitted . The 110 volts came from AC/HL a big thank you and the second one 240 volts was on Ebay not long back with the wooden case and all the leads to go with it. I hope this will be of help to Ben and his Wife.

Kevin
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Old 28th May 2022, 10:40 am   #14
Ben Humphrys
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Default Re: Restoration of vintage Triplett 1632 signal generator

Kevin thank you very much, yes the photos are very helpful. Our unit is very similar and in very good condition, but missing the wooden case, the centre tuning knob and the external termination box and lead assembly. From the circuit diagram and description it's possible to guess what to expect the external box to look like, but your pictures confirm it brilliantly.

I'm just putting together orders for Digi-Key, and others, to get hold of the bits and bobs needed to create a new termination box, also a new knob and following AC/HL's advice some Y2 safety capacitors to replace the four shown on the schematic because we don't want magic smoke. The circuit says that the filter capacitors and inductors are all inside a single can, so I'm going to investigate how to get inside it.

I suppose the user just had to remember what "D" "C" and "DD" all mean on the switch. I may decide to put other, more explanatory descriptions rather than these cryptic apparent references to bra sizes.

I'm going to run it from a 110V step-down transformer. I found a small cheap unit online.
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Old 28th May 2022, 9:15 pm   #15
Ben Humphrys
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Default Re: Restoration of vintage Triplett 1632 signal generator

Kevin,

Our internals look slightly different to yours:

There's a extra metal can on ours (photo 1) with two coils inside it (photo 2). These may be the RF suppression chokes shown on the schematic (photo 3); perhaps a little surprisingly air-cored. Then, in which case, the capacitors aren't inside the can as the pencil annotation states. Nestling underneath are four menacing-looking paper capacitors which look likely to be those (photo 4).

The coil windings are suspiciously dark in colour, maybe they have been getting a little warm. Putting them inside a can may not have been a good move by Triplett. Would it be heretical, I wonder, to create some ventilation holes in the can?

Joy unbounded! we also have a 1MHz crystal.

These old masterpieces are fascinating aren't they. They tell a little story. Ours have a sticker inside them showing 'Reformed date' (Photo 5) which my eye seems to interpret as 1953. I wonder what was re-formed then?.
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Old 29th May 2022, 10:40 am   #16
Kevin Hoyland
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Default Re: Restoration of vintage Triplett 1632 signal generator

Morning Ben.
I have been looking on Radiomuseum and Antique Radio forum and all the 1632s have the 2 coils fitted to them so I will have to take my other one a part I have and see if it has the 2 coil fitted to it and then work out why my 240 volt one has it missing. Will post more photos later. Ben can you post a photo of all the Tube line up yours looks have a socket nearer the meter for the small tube you have fitted.

Kevin
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Old 29th May 2022, 12:17 pm   #17
Ben Humphrys
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Default Re: Restoration of vintage Triplett 1632 signal generator

Oh dear Kevin, I'm so sorry. I honestly didn't mean to cause any trouble.

Here is a photo of the chassis with valves repopulated.

Bottom Left: 80
Bottom Right: 6F7
Middle Left: VR150
Top left: 6F8G
Top Middle: 6SA7
Top Right: 615

I am right now looking out for a suitable vintage knob.

Kind Regards.
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Old 31st May 2022, 10:27 am   #18
Kevin Hoyland
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Default Re: Restoration of vintage Triplett 1632 signal generator

Morning Ben Thank you for the photo I have had time now to look at both of the 1632s the 110 volt one is just as yours is but the 240 volt supply one has a 110 / 240 volt transformer fitted and no 80 Tube or the coil as in your photo I know the coil and the 80 tube all connected to the 110 transformer but the 240 volts one looks like if has never had an 80 tube or coil fitted to me it looks like it left the factory made for 240 volts.

I will post photos in the next Thread.

Kevin.

PS Ben looking at the photo both have no coil fitted.

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Old 31st May 2022, 10:46 am   #19
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Default Re: Restoration of vintage Triplett 1632 signal generator

Morning Ben.
More photos. Ben in the photo you can see an wave form on number 4 photo this is the 240 volts one.

Kevin.
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Old 31st May 2022, 9:17 pm   #20
Ben Humphrys
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Default Re: Restoration of vintage Triplett 1632 signal generator

Hmm, Thanks Kevin.

All this information is really helpful.

I've been thinking a bit about it, and guess from a position of complete ignorance that maybe the mains coils and capacitors are intended to reduce the amount of RF which could get back onto the mains wires, which the set under test may pick up. But that's complete speculation.

In which case the generator may work fine without the RF suppression coils & caps, for our purposes. Who's to say that this vintage kit would meet modern EMC requirements anyway?

It looks as though your 240V unit, I'm guessing that's the one on the left in your underside picture, has been extensively re-capped. The one I have is almost identical to the on on the right in your pic, all original wax caps. I'm hoping against hope that the unit may work without changing many capacitors. I'm thinking (never having done it) that we probably don't need fantastic performance for aligning broadcast band wirelesses as long as the generator at least oscillates. And I'm only a hobbyist seeking a little bit of fun. So I've ordered a Variac, so that I can bring the Triplett up gently.

The six (or so) screws which hold the case front panel to the case back in mine are not original, they have been replaced with shiny self-tappers. I wonder whether you have the original case screws on either of yours? Are they imperial threads, do you reckon? And what's the thread diameter, if you don't mind me asking?

Later, particularly in the absence of affordable wobbulators I'm wondering (possibly, maybe) whether some more fun could be had building a sweep gen/ wobbulator, using a DDS.

https://www.nutsvolts.com/magazine/a...ent-instrument.

Though even that is probably looking a fair investment in component costs, so.... hmmm. What do you reckon?

I wonder whether there is any experience of that anywhere in this forum? I've looked at George Christofi's FM alignment YouTube video; he makes FM alignment look intriguing, and he's been posting chat about how important it is to use sweep alignment. So I secretly quite fancy having a bit of a twiddle to find out for myself. I'm going to do a bit of research (i.e. blundering round a bit) to see whether I can find any threads about it, but there is so much to look through in here that it all boggles the mind a little bit.

There's plenty to investigate whilst waiting for parts.
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