A, E, PU and LS marking on back panel? - UK Vintage Radio Repair and Restoration Discussion Forum

Oxford1940 · 10th May 2020, 2:25 pm

Hello,

I'm currently restoring a RAP Transatlantic Type 1. I'm fairly new to all of this!

On the rear are A, E PU and LS ports. From what I can find from past posts I'm led to believe they mean the following:

A - Aerial
E - Earth (Much speculation about this one!)
PU - Unsure of the abbreviation but I understand this is the 'Gram' port, a vintage 'Aux in' so to say.
LS - Loud Speaker.

However, my main question really is why do the PU and LS have twin ports? Is this a stereo/mono thing?

Forgive the state of the set in the photo, I've yet to clean it up!

Thanks,

Oxford

paulsherwin · 10th May 2020, 2:33 pm

PU = pickup (a crystal cartridge, roughly line level)

The sockets aren't coaxial but take eighth of an inch wander plugs (like 4mm banana plugs only smaller) so you need two. For the PU, one is signal and the other is earth (chassis).

Oxford1940 · 10th May 2020, 3:53 pm

Great, thanks Paul!

Radio Wrangler · 10th May 2020, 4:37 pm

The contention about the E socket relates to differences in house wiring, not differences in sets.

Look up 'PME' and you'll find lots (too much) of discussion. Suffice it to say that if you have a modern house, or one that's had supply updates done using combined earth and neutral via armouring wires, you breach the wiring regulations if you bring an external earth connection into your house... or take any form of earth from the indoors wiring (or plumbing!) outdoors. It's dangerous and may void your insurance.

When I saw the thread title it took a moment to realise it wasn't a baby's name!

David

Herald1360 · 10th May 2020, 4:50 pm

Be wary of the LS output sockets- they may go to the primary of the output transformer (HT+ and Anode) rather than the speaker voice coil secondary

stuarth · 12th May 2020, 5:36 pm

Really, David, how can you confuse A, e, pu, ls?! with a baby’s name? You can type it on a standard English keyboard, and there are no numbers in it, let alone an aircraft type!

Stuart

paulsherwin · 12th May 2020, 7:14 pm

Quote:

Originally Posted by Herald1360

Be wary of the LS output sockets- they may go to the primary of the output transformer (HT+ and Anode) rather than the speaker voice coil secondary

While that's not impossible and certainly worth checking, it seems very unlikely in a late 30s domestic set.

Herald1360 · 12th May 2020, 7:46 pm

You'd think so, but......

See attached snippet.

Worth a careful check!

paulsherwin · 12th May 2020, 7:55 pm

Fair comment.

kalee20 · 13th May 2020, 1:20 pm

My Ever Ready 5033 does, too. Late 1930's.

Fingers on the exposed sockets (where the metal is rolled-over onto the Paxolin) is straight to HT+!

Radio Wrangler · 13th May 2020, 1:35 pm

And HT reservoirs on a valve set can retain significant charge for a fair time after they've been turned off.

Yes, those rolled copper connections..

I suppose you can estimate the voltage from how long it takes someone's eyebrows to come back round to the front.

David

10th May 2020, 2:25 pm	#1
Oxford1940 Triode Join Date: May 2020 Location: Cambridgeshire Posts: 16	A, E, PU and LS marking on back panel? Hello, I'm currently restoring a RAP Transatlantic Type 1. I'm fairly new to all of this! On the rear are A, E PU and LS ports. From what I can find from past posts I'm led to believe they mean the following: A - Aerial E - Earth (Much speculation about this one!) PU - Unsure of the abbreviation but I understand this is the 'Gram' port, a vintage 'Aux in' so to say. LS - Loud Speaker. However, my main question really is why do the PU and LS have twin ports? Is this a stereo/mono thing? Forgive the state of the set in the photo, I've yet to clean it up! Thanks, Oxford Attached Thumbnails

10th May 2020, 2:33 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,970	Re: A, e, pu & ls?! PU = pickup (a crystal cartridge, roughly line level) The sockets aren't coaxial but take eighth of an inch wander plugs (like 4mm banana plugs only smaller) so you need two. For the PU, one is signal and the other is earth (chassis).

10th May 2020, 3:53 pm	#3
Oxford1940 Triode Join Date: May 2020 Location: Cambridgeshire Posts: 16	Re: A, e, pu & ls?! Great, thanks Paul!

10th May 2020, 4:37 pm	#4
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: A, e, pu & ls?! The contention about the E socket relates to differences in house wiring, not differences in sets. Look up 'PME' and you'll find lots (too much) of discussion. Suffice it to say that if you have a modern house, or one that's had supply updates done using combined earth and neutral via armouring wires, you breach the wiring regulations if you bring an external earth connection into your house... or take any form of earth from the indoors wiring (or plumbing!) outdoors. It's dangerous and may void your insurance. When I saw the thread title it took a moment to realise it wasn't a baby's name! David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

10th May 2020, 4:50 pm	#5
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: A, e, pu & ls?! Be wary of the LS output sockets- they may go to the primary of the output transformer (HT+ and Anode) rather than the speaker voice coil secondary __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

12th May 2020, 5:36 pm	#6
stuarth Heptode Join Date: Feb 2010 Location: Heysham, Lancashire, UK. Posts: 669	Re: A, E, PU and LS marking on back panel? Really, David, how can you confuse A, e, pu, ls?! with a baby’s name? You can type it on a standard English keyboard, and there are no numbers in it, let alone an aircraft type! Stuart

12th May 2020, 7:46 pm	#8
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: A, E, PU and LS marking on back panel? You'd think so, but...... See attached snippet. Worth a careful check! Attached Thumbnails __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

12th May 2020, 7:55 pm	#9
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,970	Re: A, E, PU and LS marking on back panel? Fair comment.

13th May 2020, 1:20 pm	#10
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,088	Re: A, E, PU and LS marking on back panel? My Ever Ready 5033 does, too. Late 1930's. Fingers on the exposed sockets (where the metal is rolled-over onto the Paxolin) is straight to HT+! Attached Thumbnails

13th May 2020, 1:35 pm	#11
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: A, E, PU and LS marking on back panel? And HT reservoirs on a valve set can retain significant charge for a fair time after they've been turned off. Yes, those rolled copper connections.. I suppose you can estimate the voltage from how long it takes someone's eyebrows to come back round to the front. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done