Unrecognised Old "Spy Radio" (Mk. 301)

[coopzone]

Hello,

(my first post, please be kind!)

I have an old valve shortwave receiver, I originally purchased it from an ex-military yard in cheslyn-hay, west mids some time around 1973. It was advertised as a post ww2 "spy radio".

It seems to be a 4 wave band S/W AM/CW receiver (wave change by plugging in a squire shaped block numbered 1-4).

Power supply is external (and never been with the radio) of 90v and 1.5v.

It has an headphone socket and connections for aerial and earth

See photos please.

I was wondering if anyone has any further info?

Coopzone

[Station X]

It's a Mk. 301.

http://www.cryptomuseum.com/spy/mk301/index.htm

[coopzone]

Thats great, thanks for the info. Now all i have to do is decide what to do with it! It's not really my thing anymore.

Thanks

Coopzone

[Station X]

Your best bet is to sell it on eBay.

I have always wanted one of those, very interesting set.

[David G4EBT]

An interesting set and an excellent write-up at the 'Crypto Museum' (a 'virtual museum' in the Netherlands). I'm trying to imagine in what circumstances such a receiver would be used. 'Clandestine' means 'secretive, concealed' if used by spies, they need something that's lightweight and small. Whilst it is small - the smallest set of its kind in the era it was made (1954) - I wouldn't say that it's 'miniature', nor could it be described as lightweight or easily concealed. The valves are referred to on the website as 'sub miniature' - four of them are (wire ended) - but V1 is just a B7G DK96 as used in domestic portable radios back then.

The receiver, with one coil pack fitted, is roughly 7 inches x 3.5 inches x 1.5 inches, and the battery pack is the same. There are three additional coil packs, and if needed, an AC power supply, which is 5 inches x 2.5 inches x 1 inch, plus other accessories. The receiver weighs in at 2.5 pounds, (2.27kG) the battery pack the same, and the PSU is 1.5 pounds (0.7kG).

Some space was saved by the receiver not having integral band-switching, but if full coverage of all four bands was needed, three additional plug-in coil packs were necessary, (each having two coils, two capacitors and a trimmer, all in a robust coil box). Some space was also saved by not having a speaker, but space had to be found for the phones, and there were other accessories too. The whole caboodle consisted of:

Receiver
Coil Box Assembly
Battery Box Assembly
Battery Lead Assembly
Earth Lead Assembly
Areal Lead Assembly
Aerial & Earth Lead Spool
Phones Complete

Quite a heap.

It was designed by HM Govt's Communications Centre, and the write-up states that the receiver was intended for several services that were controlled by Hanslope park (UK), and later adopted for use by the Army's Special Forces as well. It appears to have continued to be in use until it was replaced in 1970 by the fully transistorised Mk.328 that had a band selector rather than a separate coil pack.

I'm not into military stuff, but I'm surprised that the MK301 set was still in use up to 1970. By whom I wonder? Heck, the Roberts RT1 domestic portable was introduced in 1958 and the Roberts RT1 in 1959, so the military must have been truly cash-strapped to have clung onto outdated valved equipment, greedy for batteries, until 1970 (a year after there were men on the moon). I'm trying to imagine a situation in which 'special forces' would want to use just a receiver without a matching transmitter, and find it curious that the MK301, smallish though it is, when taken together with the battery pack, coil packs and accessories can be considered 'concealed' or 'secretive' or for use by 'spies'.

All very intriguing, and to me, not a little puzzling!

[ms660]

David, I thought it had just one coil pack (referred to as a coil box) that did all four ranges:

http://www.cryptomuseum.com/spy/mk30...301_manual.pdf

Lawrence.

[Station X]

Little seems to be known about the true uses for so called Spy Sets post WW2.

The Mk. 128 is a good example of this.

[David G4EBT]

Originally Posted by ms660

David, I thought it had just one coil pack (referred to as a coil box) that did all four ranges:

http://www.cryptomuseum.com/spy/mk30...301_manual.pdf

Lawrence.

So it does Lawrence - well spotted and thanks for reading my post.

I was looking at the circuit, which infers four coil units, but the instructions clearly state that band-switching was accomplished by moving the box into any one of four positions.

That was clever!

Memo to self: RTFM.

[coopzone]

Thanks for all the info - from everyone.

Some of the comments are bringing back memories of when I acquired this kit, it was from an ex-mod broker (who sadly closed down some 30+ years ago). I remember riding by bike, with pocket money in hand, to his yard and seeing this radio on the shelf. At the time it was only a few pounds.

It was about 1973/4. I do remember it worked then, using 4x9volt pp3 and a D type 1.5v battery. In fact it was quite a good little radio. It's not been used since about 1975 and it's currently sitting looking sad in my recently uncovered scrap box from the loft!

Maybe I'll go by some batteries and have a play - time permitting.

Thanks everyone

[Graham G3ZVT]

Originally Posted by Station X

Little seems to be known about the true uses for so called Spy Sets post WW2.

The Mk. 128 is a good example of this.

Peri-apocalyptic EMP immunity is all I can think of.

[m0cemdave]

Originally Posted by coopzone

Thanks for all the info - from everyone.
Some of the comments are bringing back memories of when I acquired this kit, it was from an ex-mod broker (who sadly closed down some 30+ years ago). I remember riding by bike, with pocket money in hand, to his yard and seeing this radio on the shelf. At the time it was only a few pounds.

I'm guessing that was the place known as "Thacker's Yard", well-known to radio enthusiasts of the peiod.

[coopzone]

m0cemdave, Yes it was Thackers, Cheslyn Hay, Walsall.