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Old 29th Aug 2016, 9:53 pm   #1
GeoffB17
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Default R1481 set

Hello,
Just trying to clear up a bit of family history.

My grandfather had a R1481 set, the main unit and a power unit. According to a 1949 advert I've just seen, the unit was for 65-86 mcs. The only bit of the unit I still have is the little card tuning chart that fitted into the holder on the top front of the unit. How come I've kept that...?

I think my GF planned to alter the unit, so that it could be used on other channels. Would this have been Short Wave (somewhere in 5.9 - 26.1 mcs??) How much of a conversion would this have entailed. I think he might have started something.

I ended up with the units before I went to Univ, and I did use the power supply for powering an audio part of a TV set, but the two units (and my TV bit) vanished over the next 10 years or so (me at Uni, rest of family not knowing what it was, me not knowing what to do with it - nothing malicious). Of course, I now regret it all going. It was all in pretty good condition. Might it have been a viable project. As a teenager, I was fascinated by the very fine tuning drive, with gearing.

Any background much appreciated.

Geoff Barnard, Guisborough
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Old 30th Aug 2016, 10:17 pm   #2
trh01uk
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Default Re: R1481 set

Geoff,

yes, the R1481 was a rather rare variant of the much more common R.1132 receiver made for the Air Ministry. The R1132 was used as the ground end of the ground-to-air links to fighter aircraft during WWII and later, and it worked on 100 - 124Mc/s.

As you say, the R1481 worked between about 65 and 85Mc/s. And that's the limit of my knowledge of it. The R1132 had a matching transmitter (the T1131), but I am not aware whether there was a similar variant of this transmitter made to work with the R1481.

There is scant information about what the radio spectrum was used for during WWII. Not surprising really since such information would have been well up the "secrets" list. So its difficult to say what this receiver was intended to do. Short range, temporary radio links on VHF were not uncommon in WWII, and that might have been one use for it. But that is pure guesswork on my part.

Pics and details of the R.1132 are easy to find, and here is a useful page on that receiver here
I doubt whether your grandfather would have tried to modify the set to cover the short-waves, since its bandwidth would have been far too wide to be any use at those lower frequencies.

Richard
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Old 30th Aug 2016, 11:13 pm   #3
GeoffB17
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Default Re: R1481 set

Hmm..

Thanks for the above.

Doing a 'google' for the R1481 brought up an advert from Clydesdales in Glasgow selling the set, so it cannot have been THAT rare back in 1949. Priced for less than the 1132? Advert in 'Radio Constructor' mag.

I have a memory of looking inside the screened tuning section, and noting the relatively small plates or the variable capacitor, and I think that the tuning coils were each just a couple of loops (about an inch diameter) of fairly thick (2 or 3 mm) copper wire (I assume copper, it was covered in a gold-ish paint). Must have been a significant job to get the original tuning set.

My grandfather was an electrical engineer, and was building his own radios back in the 1930s, and had been a long time reader of Wireless World (I remember looking through the piles of that mag, with the massive components even compared to those of the 1960 era). So I assume he had some idea about what he was trying to do. Maybe he had THOUGHT it was a viable project, but then given up on the idea?

I assume also that Clydesdales had some sort of market for the units. Folks buying them for what??

Geoff
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Old 31st Aug 2016, 8:16 am   #4
M0FYA Andy
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Default Re: R1481 set

Geoff, a lot of surplus equipment was bought in that era simply to dismantle for the parts if it couldn't be used 'as-is' or modified easily. So a lot of stuff which was readily available then has become 'hen's teeth' today!

Andy
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Old 31st Aug 2016, 9:14 am   #5
Gridiron
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Default Re: R1481 set

I bought one of these receivers at the last Radiophile auction, in transit case with Clydesdale labels on it. Looks original from the outside but some component changes inside. I gave it a quick test, with a suitable psu and signal generator as there are no stations in the range it covers to my knowledge, and it was working although not well.
When I looked on the internet, I found information that it could have been used to intercept German aircraft radio transmissions by Y stations in late wartime.
If anyone is interested I will take and post some pictures of the set.
Regards Mike (Gridiron).
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Old 31st Aug 2016, 10:46 am   #6
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Default Re: R1481 set

Geoff,

as Andy said, a lot of equipment was brought up as a cheap source of good quality parts. I did it myself, stripping down a lot of equipment which back then was simply unrecognisable. In the late 60s/70s when I was doing that, there was very little information about any surplus equipment, so all kinds of things just got trashed to recover a few resistors and capacitors, and the odd valve.

I am not sure why a R1481 would be priced at less than a R1132. There was limited use for the 65 - 85Mc/s frequency range, with only 200kHz being available to amateurs at 70MHz from about 1956. In addition, I suspect sales would be closely allied to articles in popular mags like Practical Wireless, Radio Constructor, etc, detailing how to modify this or that bit of equipment to use it on an amateur band. I've seen a number of such articles for the R1132, but never one for the R1481.

Richard
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Old 31st Aug 2016, 11:48 am   #7
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Default Re: R1481 set

I wonder if the idea was to convert it for receiving TV sound (Band 1) ?
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Old 31st Aug 2016, 2:01 pm   #8
GeoffB17
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Default Re: R1481 set

Thanks for comments.

The other radio Clydsdales were advertising was actually the 1155, that was priced at 18/10/00 (complete, incl carriage) while the 1481 (again, comp with power unit and carriage) was 8/8/0. So less than half the price. Maybe because it had a lot less potential?

My memory is not reliable about this, as it's going back to I guess late 60s, but I think my GF was hinting at radio reception, I assume SW bands. I'm pretty sure he would NOT have been thinking of TV bands.

He prob bought the boxes about 1950. I'm sure it was sat there in his loft long before I understood what it was (I was born 1950). So this would be before any proposal to establish amateur bands about 70 Mhz, unless he had advance info about that. Again, I'm sure he hinted that he'd need to make some alterations to the unit for whatever he had in mind, I think he even had some circuit notes about it, or a spec for some new coils (tuning ?) or something like that.

Certainly, it never got done. Maybe it did turn out to be impossible, or just impractical?

Regarding stripping the units, I don't remember there being THAT many components in there. The tuning capacitor was a wonder, most other things looked pretty ordinary (and by the time I was looking I was dismantling TV chassis).

Maybe he just made a mistake in buying it??

Geoff
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Old 31st Aug 2016, 2:51 pm   #9
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Default Re: R1481 set

Geoff,

I would certainly say its impractical to modify a R1481 to the SW bands. Equally it would be impractical to modify it for the FM broadcast bands, given that its an AM receiver. It does sound like it may have been bought by mistake! I can't think of much use for an AM receiver on those frequencies back in 1950. Its just possible he though of picking up TV sound of course.

As for the price difference, it must reflect the difference in popularity of the R1132 vs R1481. And that almost certainly comes down to published magazine articles on how to use and modify these sets.

Richard
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Old 31st Aug 2016, 3:47 pm   #10
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Default Re: R1481 set

In the 1950s, of course, there was much discussion about "VHF" sound broadcasting being introduced in the UK - there was at least one proposal (by Pye) for this to use AM!

I'm wondering if perhaps your GF bought this radio in the hope that he could push it up to 90-odd MHz and receive the new broadcasts when they arrived?
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Old 31st Aug 2016, 4:07 pm   #11
GeoffB17
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Default Re: R1481 set

Maybe,

As I mentioned above, my GF was getting Wireless World regularly. Would these proposals have been mentioned/discussed in there early 50s?

I think (?) I did see the schematics he had regarding the mods he'd been planning, and I don't think they were THAT complex. I assume the changes needed to slightly increase the frequency range (up to 90 from 86) would have been less complex than the move the other way from 65 down towards 20 Mcs and thereabouts??

Geoff
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Old 31st Aug 2016, 5:25 pm   #12
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Default Re: R1481 set

I'm sure that the "Wrotham listening tests" carried out by the BBC in 1950ish would have been reported in Wireless World (The BBC reports are here http://www.bbc.co.uk/rd/publications/rdreport_1950_30 and here http://www.bbc.co.uk/rd/publications/rdreport_1954_36 )

To go up a few MHz would be do-able - probably all it would need would be to 'spread' the windings of the tune coils a bit. Going down to the low-tens of MHz would need new tuned-circuits in the front-end, and even then the variable-capacitor wouldn't have sufficient capacity-swing to cover many of the short-wave broadcast-bands without needing switched coils. An amateur-band receiver for, say, 14MHz, would be whaty I'd have done if converting this to SW. Remember that back in the 1950s most amateur voice contacts were made using classic AM.
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Old 1st Sep 2016, 11:33 am   #13
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Default Re: R1481 set

Hi All,
There was much interest in the 56Mc/s Ultra High Frequency band in the 1950's, spurred on by the excellent VHF propagation generated by the peak in the sunspot cycle in the late 50's. Maybe this is what Grandad was hoping to listen to. It probably wouldn't have been that difficult to squeeze the receiver down to 50Mhz or so from the original 65.
For Mike (Gridiron) - I would love to see some pictures of this receiver if you have time.
cheers
Peter G8BBZ
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Old 1st Sep 2016, 11:36 am   #14
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Default Re: R1481 set

Hi All,
I forgot to ask - is the receiver crystal controlled or variable tuning?
cheers
Peter G8BBZ
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Old 1st Sep 2016, 12:18 pm   #15
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Default Re: R1481 set

Hello,
There are two adverts for the R1481 on this page (From Short Wave Magazine for Feb 1948 I think). One is for a one converted to 56Mc/s.

http://www.vintageradio.me.uk/magazi...48/Ads3091.jpg

Yours, Richard
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Old 1st Sep 2016, 4:20 pm   #16
GeoffB17
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Default Re: R1481 set

Hello,

Thanks for the latest.

Yes, the 56 Mc/s band sounds a LOT more like what GF would have been interested in, also the timing is much more appropriate as he would certainly have been following things late 40s and early 50s, and that's also when he must have bought the set.

Seems much more likely that the band at 90?, which was only a 'possible' thing as well.

Regarding the question raised about tuning, from what I remember of such things, there was no Xtal, tuning was via a quite wonderful geared tuning capacitor (fascinating gearing, multiple ganged tuning elements going maybe 6" or more back from the front). Back then, I don't think I would have known what a Xtal was, but I would have spotted something 'odd'!

Thanks all

Geoff

PS - oh, I can picture the tuning cap even now. Numerous groups of plates, each shaped like (about) half a half crown (2/6p). As the plates intermeshed, there was a couple of mm still between the plates. And the thick wire coils mounted above as noted above. Not like anything else I'd seen!

Last edited by GeoffB17; 1st Sep 2016 at 4:26 pm. Reason: extra detail added via PS
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Old 4th Oct 2017, 12:56 pm   #17
dave walsh
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Default The R1481 Receiver

I bought one of these WW2 sets from a very nice and knowledgeable vendor at the Tonbridge Audiojumble on Sunday. He gave me a good discount due to it's aged condition, smashed signal meter and overall weight. It's a relative of the R1132A [I got one of those out of a skip in Liverpool years ago]. I wasn't expecting much info here but GeoffB17 started a thread "R1481 set" on 29/8/16 that covered quite a number of aspects. I then found an item on the web where the author said that his 1481 was [curiously] in a 1132 cabinet but that didn't seem surprising to me as it appears to be the same set with the former covering 65-86 megs and the latter 100-124. Then I looked on the really excellent VMARS site! At first I couldn't find anything listed but [on a hunch] went into the "RECEIVER R.1132A and ANCILLARY EQUIPMENT" heading. There are three chapters listed. The first is 20- pages on the 32A [great] but the second re the 1481 doesn't seem to be there. The third has no title. I downloaded half a dozen of the 32a pages anyway but now can't find it again-it must be me I thought it might be worth posting my story just in case anyone has any further info or references re this relatively rare item [4/19/6 from Clydesdale in October 1949]. I'm presuming there will be something in the Wireless For The Warrior series? VMARS clearly has a separate 1481 manual but I do appreciate the size of the task they face in trying to get all their unique info on line-thanks guys

As a related aside and re previous ongoing discussions, the gentleman at Tonbridge further confirmed that brand new equipment was destroyed after WW2. He told me that he lived near a Military camp and that three pits were filled in. One contained valves, another radio equipment and the third was transport related. He said someone dug into that one and many feet down, came across boxes containing unused motor bikes!

Dave W

Last edited by Station X; 4th Oct 2017 at 1:02 pm. Reason: Threads merged.
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Old 4th Oct 2017, 7:15 pm   #18
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Default Re: R1481 set

I've found the VMARS info again. It's under the manuals list at 213 if anyone is interested. Don't know why I couldn't find it

Dave W
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Old 4th Oct 2017, 7:32 pm   #19
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Default Re: R1481 set

Quote:
Originally Posted by Mr Moose View Post
Hello,
There are two adverts for the R1481 on this page (From Short Wave Magazine for Feb 1948 I think). One is for a one converted to 56Mc/s.

http://www.vintageradio.me.uk/magazi...48/Ads3091.jpg

Yours, Richard
Wouldn't mind a B2 for a tenner!
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Old 6th Oct 2017, 12:04 pm   #20
Gridiron
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Default Re: R1481 set

Here are some photos of the R1481 I have as requested by Geoff a long time ago, sorry for the delay. There is nothing in Wireless for the Warrior I know of although the R1132 is in the volume covering receivers. (WFTW doesn't cover RAF radios.)
Mike.
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