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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 17th Nov 2023, 6:16 pm   #1
sparkymike
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Default HT/LT plugs and sockets

I am searching for an HT/LT extension cable and chassis socket for a valve preamp. 6 way I believe.
Also trying to find some 250K logarithmic potentiometers with 1/4'' D shafts. All I can find are split shafts and I don't want that type.
Mike.
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Old 17th Nov 2023, 6:29 pm   #2
G.Castle
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Default Re: HT/LT plugs and sockets

Try Rapid electronics for the pots Mike.
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Old 17th Nov 2023, 6:54 pm   #3
G6Tanuki
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Default Re: HT/LT plugs and sockets

Any photos of the 6-way plugs/sockets? I wonder if they are the 6-pin Jones type?

[I'm more familiar eith these being used as power connectors on 'sixties/seventies Yaesu radios, and more recently the AEL3030 HF transceiver I rebuilt]. There are various different flavors of these depending on whether all the blades are in-line [with different spacing] or two of them are set at 90 degrees to the other four.

Mouser seem to have a range.... https://www.mouser.co.uk/c/connector...plugs-sockets/
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Old 17th Nov 2023, 9:43 pm   #4
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Default Re: HT/LT plugs and sockets

If your supplying an pre/amplifier with a combination of an AC heater and high voltage DC supply, be aware that the high current low voltage will couple with the low current, HV DC supply. If you use different cables, but on the same plug, you'll still have an issue, especially on a high gain preamp.

There are other issues too, I built a couple of 50w monoblocks supplied from a separate PSU & used different plugs/sockets for both AC & DC supply's but had an issue with a mains earth loop. If you have a metal chassis for your amp, apart from the earth loop issue, how will it be mains earth referenced?

Don't want to put you off but using a separate PSU & amp throws up a few issues, as highlighted above. In my case I used military connectors for everything but HT, for that ( 500v ) I used a PL529 plug/socket - https://uk.farnell.com/amphenol-rf/p...ble/dp/2305443 I've not had an issue.

For lower voltage higher current stuff Speakon does a wide range of stuff but some are not cheap. Which brings up another potential problem. Any connector you use must be idiot proof, EG someone who hasn't your knowledge could get a belt off an incorrectly constructed cable. For a preamp with separate PSU I built, I made sure HT out was a female socket & made doubly sure by using a relay to disconnect HT too, with bleeder resistors on all HV caps.

Again,sorry if this is telling you had to suck eggs, Andy.
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Old 19th Nov 2023, 9:41 am   #5
sparkymike
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Default Re: HT/LT plugs and sockets

More details of the plug.
It is an 8 way plug, possibly Bulgin, and it is for plugging into a Beam Echo DL7-35 amplifier for LT/HT supplies to a preamp.
I had thought it was 6 way, forgot about the on/off switch wires.
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Old 19th Nov 2023, 9:49 am   #6
sparkymike
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Default Re: HT/LT plugs and sockets

Hi Andy, take on board all you say, but Quad did it and also many others such as Leak and Rogers. How did they do it without problems ? Screened multicore with twisted heater wires ? They were not too long interconnects, screen I presume was connected also to chassis earth for extra safety ?
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Old 19th Nov 2023, 11:32 am   #7
barrymagrec
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Default Re: HT/LT plugs and sockets

Looks like a standard Octal plug / socket arrangement, Bulgin certainly did these as did others.
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Old 20th Nov 2023, 3:08 pm   #8
sparkymike
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Default Re: HT/LT plugs and sockets

Just tried a 6L6 valve in the 8 way socket on the amplifier and is fits exactly, so now I have a choice, make one out of a valve base, or find one on the net. I have located the sockets but so far not the plugs.
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Old 20th Nov 2023, 3:41 pm   #9
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Default Re: HT/LT plugs and sockets

Packs of 4 on eBay, £9.99+post https://www.ebay.co.uk/itm/275312589011
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Old 21st Nov 2023, 9:48 pm   #10
sparkymike
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Default Re: HT/LT plugs and sockets

A few on ebay and several from the USA but with around £19.00 extra postage !! The Bulgin type with the long rear cover would be the prefered item I think.
Will keep searching.
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Old 28th Nov 2023, 11:23 pm   #11
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Default Re: HT/LT plugs and sockets

This any good?

https://www.ebay.co.uk/itm/186176837...h=item2b590117

You would probably need to make up the lead to suit but the covers are there as well as the plug and socket.

Cheers

Mike T
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Old 29th Nov 2023, 9:13 am   #12
sparkymike
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Default Re: HT/LT plugs and sockets

Now got the plug but have been looking for a chassis mount octal male, but so far they don't seem to exist. I could use an octal valve base, thanks to Terry,, but that makes for a dangerous lead, if anyone unplugged it while still switched on. I guess only way is to use a cable gland on the pre-amp. That would give me more room inside the box.
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Old 29th Nov 2023, 5:58 pm   #13
ronbryan
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Default Re: HT/LT plugs and sockets

Hi Mike


I have a NOS octal chassis plug, made by McMurdo (see photo). Yours for £6 plus £3.49 second class small parcel if you want it.
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Old 29th Nov 2023, 8:08 pm   #14
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Default Re: HT/LT plugs and sockets

Hi Mike, try an octal based relay

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