Rear Panel Mains Connectors

[Kiki009]

My very early AR88 which I have almost finished restoring, came with "Bulgin type" 3 pin plug and socket about 23 cms across as standard.
It still has the blue paint on the fixings as do other components around the chassis.
I wondered if this was standard practice for the early versions of the AR88?
Chassis number:SC197A, Serial number:0016811, Solid yellow dial....since changed as the original had been cleaned, and we know what that does :-(
Engraved front panel, and original "S" meter.
The only slight problem I have left is the 6K6 running hotter than I would expect and slight distortion at higher volume levels...working on that, then complete.
This receiver was built in the year that I was born going by the inspection tabs left inside the case, so the family recon I should keep it for nostalgic reasons...huuuray.

Bob(UK)

[Chris Parry]

I wouldn't expect a Bulgin power connector to be original to any AR88. Chris.

[Kiki009]

Originally Posted by Chris Parry

I wouldn't expect a Bulgin power connector to be original to any AR88. Chris.

I agree Chris, this was a "Bulgin type" I can't remember the correct name for it, 3pin plug and socket, not the normal smaller version.
This one is 2.3 cm across (23mm) and came with the original cloth covered main lead.
As I said, every screw and nut along with nearly all the soldered connections had a splash of blue paint on them.....so did this mains socket, and the receptacle looks as though it was factory made....rather than a later modification IMO.
So I think this may have been yet another variant, it is a very early one after all.

Rgds Bob.

[Chris Parry]

Hello Bob, My own guess is that it left the factory in standard form but was modified almost immediately, on its entry into active service. For example if it went to sea with the Royal Navy (as a very few early AR88s did), the captive mains lead would probably have been replaced with some sort of connector to make it safer to drag up ladders & along wet companionways. A Bulgin, though? Very odd choice, that is. Chris.

[Kiki009]

Originally Posted by Chris Parry

Hello Bob, My own guess is that it left the factory in standard form but was modified almost immediately, on its entry into active service. For example if it went to sea with the Royal Navy (as a very few early AR88s did), the captive mains lead would probably have been replaced with some sort of connector to make it safer to drag up ladders & along wet companionways. A Bulgin, though? Very odd choice, that is. Chris.

Hi Chris, I suppose that is a possibility although I thought that the early Royal Navy ones that actually went to sea were battleship grey.
Your explanation makes sense though.
I have an Advance signal generator that has the same 3 pin mains socket, it was manufactured around the same period, so I wouldn't be surprised if this type of connector was chosen for it's robustness and maybe readily available at the time.

Anyway, back to sorting out my hot 6K6 problem, I will be checking the biasing and grid components today, and taking more voltage readings at different volume levels.

Bob.

[Kiki009]

Chris, there is a thumbnail of the signal generator here from an earlier post.
https://www.vintage-radio.net/forum/...2&d=1325950043
Bottom left hand corner, you will see the same type of 3 pin connector found on my version of the AR88.

Bob.

[Chris Parry]

Yes, that Bulgin was a very popular type of connector >here in the UK< but surely not stateside. Chris

[Kiki009]

Originally Posted by Chris Parry

Yes, that Bulgin was a very popular type of connector >here in the UK< but surely not stateside. Chris

OK, in that case do any other AR88 owners have a version that used blue inspection paint on all the soldered connections and nuts and bolt fixings?
If so, maybe I can discover who modified my version and why.
Mine also has a SO239 on the back panel close to the antenna connections connected to the Xtal load transformer.

Bob.

[Chris Parry]

When I started this thread, I had hoped for a small round connector that I could use as an upgrade for the 3-pin mic plug/socket that I have fitted until now on the rear panels of my heavier radios. I send my grateful thanks to all the various contributors.

I now know there are more connectors out there than I was aware of before. But not one of them is as small as the 3-pin mic socket. I can certainly say that the 3-pin free mic line socket will accept "ordinary" 3-core mains cable. To reduce risks, I always link the metal outer shell of this connector to the earth conductor of its mains cable, and I never fit or remove the connector whilst under power.

The chassis sockets are generally straightforward to fit. Cutting the necessary holes in the AR88 and suchlike radios having a sheet steel rear apron is not easy, but a lot more practical than cutting anything larger. The two BRT400s here, now have 1/16" FR4 laminate adaptor plates to allow the 3-pin mic chassis plug to fit into the rectangular aperture cut by GEC for the original horrible bespoke connector. Eddystones are a special case. On many models, they used a 2-pin mains connector with a flat earthing blade. I am not changing these en masse, however I always fit a separate earthing wire because I cannot bring myself to trust the original arrangement. At 99lbs, the Eddystone S880/2 was the second heaviest of their HF models and perversely, this one has a captive mains cable. The topography of the rear panel precludes the fitment of any connector. So next time it's on the bench, this radio will be fitted with a short tail to an IEC free line plug. My other heavy radios follow one or other of these approaches.

As is obvious, there are safety hazards in using a 3-pin mic plug/socket to carry mains voltages. I do NOT recommend this approach to others. But for me, it enables a compromise that I can live with pro tem. Maybe one day I will find a connector with the same chassis footprint as a 3-pin mic plug. I hope so, anyway.

Chris Parry.

[glowinganode]

Originally Posted by Chris Parry

a 3-pin mic plug/socket to carry mains voltages.

As in 1/4" stereo jack plug?
Rob.

[Chris Parry]

This is the "Foster" series of connector as used on Jap ham radio transceivers in the 70s & 80s for headsets & microphones. I use the 3-pole 270deg type. Chris.

[glowinganode]

Ah, ok. Like this one?
Rob.

[Chris Parry]

Yes. Same shell but only three, larger diameter pins. Chris.

[turretslug]

Bit late in the day now, but I found I had managed to save a small number of Souriau mains connectors from oblivion- the panel connector needs a 20mm fixing hole, the fixing holes are M3 clear on a 21mm square. On reflection, as raised by others, a short flying lead with a line IEC plug sounds sensible, as it would part easily and safely under stress- the Souriau (and others) latch very firmly indeed.

At lest the "mic" connector is no worse than that 3 pin Plessey connector found on much ex-ministry stuff! I fitted a Souriau on my B40 in place of the original 2 pin Plessey. Apologies to purists- originality is nice but safety first.

Chris, as the OP, I'd be happy to drop a Souriau pair in the post- but I apppreciate you probably want fleet consistency, connector-wise.

Colin.

[Chris Parry]

Thankyou for this. Souriau connectors are very nice, but I'll not take you up on your very kind offer because I know the direction I'm headed now. Chris.