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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 25th Oct 2018, 12:37 pm   #1
its ur aerial
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Default Murphy B40 or B41 Purchase.

I have been given the opportunity to purchase a Murphy B40 and or a B41.
I know the B41 has the ability to tune to LF Bands, which is not of any use to me, ( its wanted for 80M VMARS AM net use) Is one model better or later than the other.Apart from the AF output fault, any other common obvious faults to look for when inspecting ?
Any comments appreciated.
Ken, G6HZG.
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Old 25th Oct 2018, 12:53 pm   #2
Dave757
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Default Re: Murphy B40 or B41 Purchase.

Hi Ken,

The B41 would not tune to 80m (it only goes up to about 700kHz)
so is not an option.
I have used a good few B40s, but I wouldnt really buy any other than the B40D
as it has the most useful facilities.
I can't comment on the faults as I never had any problems with mine
but I found it a very decent set.
As a friend of mine commented, - if it was half the size it would be worth
four times the money.
Incidentally as the IF is exactly 500 kHz you can easily connect a frequency counter to the LO
for digital readout (allowing for the 500kHz offset of course!)

Kind regards
Dave G0ELJ

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Old 25th Oct 2018, 1:14 pm   #3
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Default Re: Murphy B40 or B41 Purchase.

Dave,
Thanks for the info, no point in the B41 then. I was once informed it was the later
version with smaller moden valves and a LF band for Submarine use.
Obversely I was misinformed.
Thanks again Dave.
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Old 25th Oct 2018, 2:04 pm   #4
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Default Re: Murphy B40 or B41 Purchase.

There is also a Murphy 62B of the same mechanical and similar electrical design that covers LW and MW broadcast bands and 3.9 - 30.5MHz SW using miniature valves- perhaps they were thinking of this?

Wonder where the "submarine" association originated- at one point, an ex-submariner is supposed to have made a slightly flippant, typically Services offhand black humour remark to civilian journalists along the lines that if Radio 4 LW couldn't be heard, then surely civilisation had come to an end and it was time to vaporise the USSR, and it all got taken a bit too seriously.... Maybe the "LW receiver" association arose thus! The B41 in submarines for VLF use is entirely credible, though.

https://www.radiomuseum.org/r/murphy_62b62.html
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Old 25th Oct 2018, 10:39 pm   #5
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Default Re: Murphy B40 or B41 Purchase.

I've had a B40D for a while now, was sort of working when I got it, things to look out for, I can only go on my experience, set had been got at, backlash in tuning mechanism, chain tensioner bodged, sticking switch mechanisms for LS and mains, set had been dropped, chassis bent, missing brackets behind front panel, wobbly fine tune control on the D version, two of the grey smoothing caps burst and leaking oil, almost all of the resistors have gone high but still works okay, shorted decoupling caps (the brown rectangle ones), crackly bandwith switching (not sorted yet), smoothing choke went o/c.

D set has low impedance ant input, some have been modified low value cap from ant to first tuned grid RF amp .A B C versions high.

You will need safecrackers fingers to tune SSB or CW.

Mine is in regular use monitoring SW AM intruders, copes well with the high level of wideband coherent noise at my location which saturates a receiver with an untuned front end. Twenty quid should get a complete but working project, up n down from there.

T
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Old 27th Oct 2018, 7:07 am   #6
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Default Re: Murphy B40 or B41 Purchase.

Thanks for the replies, I was told a similar story by a ex Submariner I once worked with, if they were in range, but could not receive Radio 4 LW, assume the worst.

If the B40 on offer is not basically working or is not a easy project I wont bother, just not got the time.
The curious thing is, when I was a young SWL in the 60`s I don't ever remember hearing a Amateur ever mentioning he had a B40, unlike the CR100, HRO and of course the AR88.
I vaguely remember seeing them advertised by the likes of GW Radio etc, at what would seem a the rather expensive price of £75 ! But I could be wrong, because then you could still get a new AR88 in a box for £85.
Why were they not popular, was it just the weight and assectics ?
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Old 27th Oct 2018, 10:33 am   #7
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Default Re: Murphy B40 or B41 Purchase.

Hi Ken,


They seem to go for very little money these days - my B40C cost less than 10p/lb! It worked OK from the outset, albeit a bit deaf. Probably needs some leaky caps replacing. Due to the weight it never got further than the garage workbench and I'm concerned that arthritic hands will eventually prevent me from changing wavebands! It's worth making sure the chassis is earthed separately in case the mains connector doesn't do it's job properly. I've also still to find the correct 4 pin connector for the aerial.
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Old 27th Oct 2018, 1:30 pm   #8
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Default Re: Murphy B40 or B41 Purchase.

My wife and I have been watching "The Crown" and the episode we watched last night featured the Royal Yacht Britannia on a round-the-world cruise with Prince Philip aboard.

My ears pricked up when some nice CW appeared, supposedly from an Australian warship that had rescued a fisherman who needed serious medical attention. A brief shot of the Britannia's radio room showed what looked a whole rack of B40s to me but I wasn't fast enough to pause the programme for a closer look. There was an Eddystone cabin receiver in a later part of the episode too.

Memo to film makers, good to hear real CW but an urgent medical assistance message would be an "XXX" not "SOS"! Pedantic, moi?

Cheers

Roger
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Old 27th Oct 2018, 10:03 pm   #9
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Default Re: Murphy B40 or B41 Purchase.

I'm a bit of a B40 fanatic - Although space has precluded my keeping the 6 that I had here last year.

Generally, the B40D is the most desirable, and uses easy to find valves.

The B40 A, B and C have valves that are slightly harder to find.

The 62B was designed as part of the Ships Entertainment, and as such is really a rather nice broadcast receiver.

The B41 is indeed a VLF RX, not particularly useful, but if you want to collect a set.....

If you can find a D, then go for it - they are reasonably easy to work on, and accessibility to all the common suspects - Drifting resistors, and Leaky capacitors is relatively simple.

You may find making up a set of service leads will be helpful - the PSU, and AF stages sit on the bottom chassis, and are very difficult to access whilst plugged in.

Connectors for the antenna and audio are around, you just need to ask the right people - you will be needing Plessey Mk 4 connectors, the smallest size available, 2 pole, 4 pole, and 6 pole female - a good modification that I carry out on mine is to change the mains connector for a three pole, as per the RA17, or AVO CT160.

Documentation is available on line, and a numberof members here have one or more of them.
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Old 29th Oct 2018, 6:14 am   #10
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Default Re: Murphy B40 or B41 Purchase.

Sean,
many thanks for the useful information, all appreciated.
Not sure what model B40 is up for sale, but hopefully its the D version.
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Old 29th Oct 2018, 8:15 am   #11
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Default Re: Murphy B40 or B41 Purchase.

The B41 makes a useful signal tracer as it covers all of the common IF frequencies, not forgetting SAQ Grimeton on 17.2.

Jim
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Old 29th Oct 2018, 10:23 pm   #12
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Default Re: Murphy B40 or B41 Purchase.

Quote:
Originally Posted by its ur aerial View Post
Sean,
many thanks for the useful information, all appreciated.
Not sure what model B40 is up for sale, but hopefully its the D version.
Hello Ken.

B40D easily identifiable from the presence of the 'fine tuning' control, as shown.

Regards
Pete
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Old 16th Jan 2019, 10:01 pm   #13
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Default Re: Murphy B40 or B41 Purchase.

For those interested in service leads. I have never seen them but i decided to make my own. See my post...

https://www.vintage-radio.net/forum/...ad.php?t=70722

One of the issues in older B40 types. The ones with the metal shield valves. The modification manual BR1617 (B40)and BR1618 (B41) say something about the faulty CV327. I will post the scans/pics here.
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Old 16th Jan 2019, 10:02 pm   #14
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Default Re: Murphy B40 or B41 Purchase.

Heres the same mod for the B41 receiver.
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Old 16th Jan 2019, 10:06 pm   #15
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Default Re: Murphy B40 or B41 Purchase.

Service leads were mentioned so i will post info about them here. Because I have never found any (do they exist?). I decided to design them on my own and make a pair. Based on the BR1617 manual and added comment of Vintageradionet memebers. The info is found here .. https://www.vintage-radio.net/forum/...ad.php?t=70722
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