Wanted smaller than 1/4" jack plugs :)

[M0AFJ, Tim]

I've got a Drake TR4C running but the stereo and mono jack plugs used for the mic and key connections are a tad smaller than the standard 1/4". (3/16"), They are available from the USA but I was just wondering if anyone had any of these in their junk boxes that I could purchase.

Tim M0AFJ/G8GGP

[Tim]

I think these are know as "Bantam" plugs. They are a sort of mini version of the GPO jack plug. Have a look on the Canford Audio website and see if they look right.(also try Studio Spares).


http://www.canford.co.uk/Products/43-133.aspx



Catalogue info attached

[M0AFJ, Tim]

Thanks Tim, very useful. I'm not certain about these though I'll try ordering a couple to try.

Cheers
Tim

[Antlong]

Hello all,

The Bantam plug is a smaller version of the long-established Post Office jack and I'd thought they would only be found in professional telephony and broadcasting equipment. But I'm no expert.

I'm fairly certain that I have a slightly smaller "domestic" jack plug in the junk box but I can't check 'til Friday, sorry.

The two types are known I think as "Gauge A" and "Gauge B" but I could never remember which was which; in my bit of the BBC they were "PO" and "Igranic"...

The PO style plugs were a real pain for low-level audio pluggery, they needed to be absolutely clinically clean - they were designed for telephony use where DC wetting helped avoid contact problems.

Regards Ant

[Neil F]

General Aviation headsets are fitted with two jack plugs: the standard 6.3mm (1/4 inch) for the headphones and a slightly smaller one (around 5.25mm or 1/5 inch) for the mic. These latter are larger than the 'bantam' ones and might be what you're looking for. I don't know of a supplier, though!

[Tim]

The PO style plugs were a real pain for low-level audio pluggery, they needed to be absolutely clinically clean - they were designed for telephony use where DC wetting helped avoid contact problems

I believe BBC engineers used to sandpaper them to get a bright finish. "Scotchbrite" is just as effective and the plugs don't end up like a matchstick! These days plated versions of the BPO plug are available. I found one of these "Bantam" plugs today( on the end of a lead--in use!!) and it is about 2/3 size of a normal BPO jack.

[Antlong]

Hello Tim,

Well, I can't speak for the engineers but us ex-Control Room, Recordings, SM and OB types used Brasso and similar, or that PO tape impregnated with ?Brasso!

Regards Ant

[russell_w_b]

Originally Posted by Tim

I believe BBC engineers used to sandpaper them to get a bright finish.

We certainly did not! They'd end up like 3.5mm plugs before you knew it! 'Scotchbrite', as you say, and 'Brasso'. Wire-wool never used to be allowed on transmitting stations (I was told that when I once looked for some for the very purpose of cleaning a plug), so we never used it.

Did you know there was a device produced, a bit like a pencil sharpener, for cleaning BPO plugs?

Going back to the plug in question: what sort of length is it? I had some USA 'Utah' headphones with a funny plug on the end, like a ring-tip 1/4-inch plug, but it was shorter than a standard 1/4-inch plug. Maybe they were common on USA stuff?

[M0AFJ, Tim]

Thanks everyone, the plugs required are the aircraft type which I could not get in the UK for love nor money so I've bought 5 from the USA at large cost, of course in the UK nobody makes things do they, anyway they have arrived and I expect to have my Drake TR4C running tonight on 80.
The recovered audio on the Drake is superb, much better than my other rice boxes!, now to find a T4X and R4C.

Tim M0AFJ/G8GGP

[Antlong]

Hello Tim et al,

Glad you're fixed up - save me delving in the garage!

I have what might be the innards of Russell's cleaner - an "inside-out" wire brush, a metal cylinder with the wire bristles pointing inwards. We experimented with it in a drill but it was too much, too fast. Perhaps now that we have electric screwdrivers etc but hey, it's no longer my problem!

Regards Ant

[milairuk]

Originally Posted by M0AFJ

Thanks everyone, the plugs required are the aircraft type which I could not get in the UK for love nor money so I've bought 5 from the USA at large cost, of course in the UK nobody makes things do they, anyway they have arrived and I expect to have my Drake TR4C running tonight on 80.
The recovered audio on the Drake is superb, much better than my other rice boxes!, now to find a T4X and R4C.

Tim M0AFJ/G8GGP

These are also called PJ068, found them here :
http://www.flyingshop.com/proddetail...rophone%20Plug
I know it's too late for you but may be of help to others. Also made in Germany by Telegartner (or they were when I manufactured Aircraft headsets some years ago)
73
John

[Valleyjinker]

Originally Posted by M0AFJ

Thanks everyone, the plugs required are the aircraft type which I could not get in the UK for love nor money so I've bought 5 from the USA at large cost, of course in the UK nobody makes things do they, anyway they have arrived and I expect to have my Drake TR4C running tonight on 80.
Tim M0AFJ/G8GGP

The Aviation microphone plugs are the same ones as on the TCS12 Collins transmitters - I think the 'aviation low impedance' microphone standard originally came from that series of radios during the war. They used carbon mics, so there's a fairly heavy bias current available, not suitable to go directly onto an electret mic.

Pilot-Europe could probably supply modest quality overmoulded plug leads at a modest price - 01243 870999. The usual ones from the 'States are made to a very high quality.

[milairuk]

Originally Posted by Valleyjinker

They used carbon mics, so there's a fairly heavy bias current available, not suitable to go directly onto an electret mic.

On the contrary, modern aircraft headsets use this bias voltage to power the electret mike and associated amplifier, but this is straying off topic a bit

[Valleyjinker]

Originally Posted by milairuk

On the contrary, modern aircraft headsets use this bias voltage to power the electret mike and associated amplifier, but this is straying off topic a bit

...but not directly onto the electret mic....

[Brian R Pateman]

As Tim has now obtained some of these plugs and this thread is drifting inexorably away from the original subject it is time to unplug it!

Regards,