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Old 6th Aug 2020, 12:38 pm   #1
John Caswell
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Default R210 Larkspur receiver

Always fancied one of these, and managed to pick one up for £40 plus external PSU and audio amp, with the film scale in a can and the workshop manual.
Externally a bit shabby but internally almost like new.
Refitting the film scale looked a bit daunting as the set requires a fair amount of dismantling, but with the book, pretty easy. Usual problem of solidified grease and oxidised oils, all cleaned up and lubricated using moly based grease and modern oils.
Needed to be quite dexterous really, with ideally 3 hands to do the scale but managed pretty well at third attempt, and refitted it correctly as per book.
Reassembled the unit powered it up and set the film scale centrally to the cursor at 2.5 MHz injected 2.5MHz and it was pretty close, reasoned that the alignment hadn't been touched so adjusted the flexible coupler to match scale to frequency.
Tried on all other bands and very close, so a quick twice of alignment probably called for after 60 years.
Whilst on the bench I managed to knock the RF amp valve and the signal dropped in level. Tapping around the signal varied in level accordingly. Looking at construction I thought Oh *** need to take the RF unit our again. Not so, someone had put a lot of thought into the construction, as all screening panels were easily removable (excluding myriads of screws). Once panels were removed and the unit powered up, it was easy to trace the problem which was a non-soldered joint on the RF valve base cathode connections. Re-soldered it powered it up and bounced/dropped the unit around the bench - perfect. How this joint had survived over 60 years I don't know as the exterior, as I said, looked knocked about a bit
Left it running all day - minimal drift uncased so reasoned all good.
Now to make a proper PSU for it, might be able to fit it inside the case after taking out all the vibrator PSU bits and pieces, we shall see.
A beautifully made unit, easily serviceable - you can see why military equipment costs so much.
A pleasing couple of days work the satisfying results.

John
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Old 6th Aug 2020, 2:15 pm   #2
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Default Re: R210 Larkspur receiver

Good success story! Just looked on Radiomuseum to see one, looks delightful, but why would NATO want a vehicle-mounted transceiver to cover Medium Waves
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Old 6th Aug 2020, 2:22 pm   #3
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Default Re: R210 Larkspur receiver

For when they stopped for a brew up?

David
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Old 6th Aug 2020, 3:47 pm   #4
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Default Re: R210 Larkspur receiver

Quote:
Originally Posted by Julesomega View Post
why would NATO want a vehicle-mounted transceiver to cover Medium Waves
Umm, frequency coverage is 2-16 MHz isn't it?

Hugh
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Old 6th Aug 2020, 5:42 pm   #5
John Caswell
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Default Re: R210 Larkspur receiver

It is not a transceiver but a standalone 24 DC powered receiver with vibrator run internal PSU and phone output only and covers 2-16MHz in 7 bands as follows:
2.0 - 3.0
3.0 - 4.5
4.5 - 6.8
6.8 - 9.1
9.1 - 11.4
11.4 - 13.7
13.7 - 16.0.

John
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Old 6th Aug 2020, 5:46 pm   #6
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Default Re: R210 Larkspur receiver

They'd have to listen to the world service, then.

David
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Old 6th Aug 2020, 6:31 pm   #7
Julesomega
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Default Re: R210 Larkspur receiver

Ulp, I see it now Quote from Radiomuseum
1. 2 to 4 MHz
2. 4 to 8 MHz
3. 8 to 16 MHz
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Old 6th Aug 2020, 7:30 pm   #8
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Default Re: R210 Larkspur receiver

Good restoration! I got given one of these in exchange for a scope repair job a few years back. But why take out the vibrator? Mine works beautifully on vibrator with a friendly hum on 28V in. And it’s a much easier psu, as the set needs HT, LT and a -40V bias supply.
I assume you have all the circuits and connector pinouts. If not, give me a shout and I’ll drop some over at some point, or email.
-Jeremy
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Old 6th Aug 2020, 8:09 pm   #9
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Default Re: R210 Larkspur receiver

A nice fix.

I had one of them with a 'stripped' filmstrip-dial a while back: my solution was to fit a £10 chinese six-digit frequency-counter module (conveniently available with IF-subtraction by a set of DIP-switches) behind the glass window.

They're not bad receivers, if you can forgive the not-SSB-friendly 'fast' tuning-rate and the 15MHz-broadcast-band images when tuning 14MHz.
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Old 7th Aug 2020, 10:13 am   #10
John Caswell
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Default Re: R210 Larkspur receiver

Hi all,
Not a great lover of electromechanical devices like vibrators, they were always troublesome in car radios, but I see the REME workshops do a FET variation on a theme so might try one of the, and as Jeremy says, easier power supply. I may strip everything off the front panel and respray it, it would certainly look better and as it is the cast metal character version no engraving filling in to do

John

Last edited by John Caswell; 7th Aug 2020 at 10:16 am. Reason: Addn'l info
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Old 7th Aug 2020, 9:12 pm   #11
dave walsh
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Default Re: R210 Larkspur receiver

I saw some in the window of the surplus shop [opposite the Old Fire Station] at Oxford in the nineteen nineties. It was Sunday, it was shut and I was on my way North. I rang them up from Lancashire to reserve one and that was hard work-"Oh right, they'll probably be over in our warehouse !" When I eventually got back to Oxford they hadn't done that but there were three 210's left. Two were ok but the third had knobs missing or something. It was a bit rough so I tried to negotiate an all-in price for the three. No chance, to my surprise! So I said "Ok I'll just take the two good ones then" [I think they were £29-99p each]. The chap seemed to have difficulty adding up the price of two and said how about both for £40? After all that, I wasn't complaining I'd seen the SW Mag R210 conversion articles but I also just ran them off the 28v option that Jeremy went for. It was all very interesting but l didn't think the set [while it was built and performed very well] warranted me doing the work [if I could that is]. I also was beginning to recognise that preserving originality might be a good thing. It was a different story with WW2 equipment in the sixties of course. I agree these sets are pretty rugged. They remind me of the story re a US Bendix RX run over a by a truck and into the mud of a scrap yard [In The Radiophile I think] Apparently they dug it out, hosed it down and it worked

Dave W

Last edited by dave walsh; 7th Aug 2020 at 9:26 pm.
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Old 28th Oct 2020, 3:15 am   #12
John KC0G
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Default Re: R210 Larkspur receiver

For details on the design of the R210 see: J.A. Knight, "HF Band Communication Journal", A.T.E. Journal, April 1958. The A.T.E Journal was the house journal of Automatic Telephone and Electric Co., which later merged with Plessey. I have seen the article, but do not recall if I have a copy. It was referenced by Pat Hawker, G3VA, in his wonderful article "Trends in H.F. Receiver Front-ends". R.S.G.B. Bulletin, September 1963, pp 161-167.

73 John
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Old 28th Oct 2020, 7:26 pm   #13
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Default Re: R210 Larkspur receiver

Quote:
Originally Posted by John Caswell View Post
It is not a transceiver but a standalone 24 DC powered receiver with vibrator run internal PSU and phone output only and covers 2-16MHz in 7 bands as follows:
2.0 - 3.0
3.0 - 4.5
4.5 - 6.8
6.8 - 9.1
9.1 - 11.4
11.4 - 13.7
13.7 - 16.0.

John
Its odd seeing the R210 discussed with no apparent reference to its companion transmitter, the C11. It could be used "stand-alone" as John mentions above, and the army did indeed provide suitable kit to make that possible - but it must have been a rare use, because I've never seen the kit actually on the surplus market anywhere. Its mentioned in the manuals, which is the only reason I know about it.

So the R210 was really not a stand-alone receiver, it was part of a larger system, the C11/R210, which was typically used in vehicles, such as Landrovers and light lorries (like the Austin K9) which had a separate 24V power system, namely separate batteries and a separate alternator run off the engine from the normal vehicle 12V electrical system. Here's a pic of the whole lot:

Click image for larger version

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The R210 probably represents the best of the military HF sets from the era when valves were really the only option and AM & CW were the key modes used. Of course RTTY/FSK was also available with an add-on adaptor. The C11 is also a very nice unit, beautifully made, and with hi-level anode and screen mod on AM.

Both units were simple to operate, which of course for the military is a key requirement.

Richard
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Old 28th Oct 2020, 7:29 pm   #14
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Default Re: R210 Larkspur receiver

I should add to the above that there is a mains power unit provided for the C11/R210 system, so it was evidently used sometimes as a ground station. It was a replacement for the earlier (WWII era) Wireless Set No.52. Not sure it was really much smaller or much lighter though than that earlier brute of a set. The handles you can see in the pic I gave in my last post optimistically suggest you can just cart this lot about........in fact you would be foolish to attempt anything less than a 2-man lift (unless you are weight lifter!)

Richard
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