Pam/Pamphonic 607 (Pye 15A) WB June 2009

[Pamphonica]

I bought this set from WB in June 2009. I know it is based on the Pye 15A chassis. I am finally getting round to looking it over and am after information.
It has clearly been repaired relatively recently, and is all complete as far as I can see (one EBL31 missing). Of course, if the previous owner reads this, first-hand info would be useful, of course!)
It has no internal speaker but appears to have outlets for both speaker and field coil. The field socket is masked by the back-panel so is presumably not used. Would it expect a standard low-ish impedance (2-4 ohm) speaker?
Has anyone any experience of this Pam/Pamphonic variant?
Any help most gratefully received.
rgds
Jeremy

[Darren-UK]

The only information I can find is here on radiomuseum, but that tells you little more than what you can deduce by looking at the radio in front of you.

Re the internal 'speaker, your post is worded as though the radio was never fitted with one and it thus relied on an external 'speaker. Surely I've misinterpreted that, given the grille cloth and the details on the radiomuseum page?

[Pamphonica]

It is basically just a Pye 15A, but interestingly the chassis has slight modifications, and is painted red. Just like the PAmphonic 606/1 amp in my avatar photo!
No - there is no internal speaker fitted and no sign of one ever having been there. Knowing Pamphonic, everything could be customised! But it will be easy to fit a speaker inside. I have a suitable round Celestion that is c. 1951 so not too far out.
rgds
Jeremy

[Hermit6345]

HI Jezzer,

Mine has an internal energised speaker fitted. You should find that the internal voice coil conections go the a couple of sockets on the rear apron of the chassis. Normally, the voice coil of the internal speaker plugs into these sockets using a pair of wander plugs. The internal speaker is used normally. For remote listening the idea is that you remove the wander plugs and plug the voice coil of your extension speaker into the sockets thus vacated. Are you saying that there is nothing behind the large speaker fret material on the left hand front side of the cabinet? In my set that would prevent the HT from getting anywhere because the energising coil is in series with the HT supply from the rectifier. Have they replaced the energising coil with a suitable resistor? I have not compared mine carefully against the Pye 15A so I couln't comment on that. The main problem with mine was the ferrite cores dropping off the brass IF adjusters inside the IF transformer formers.


Ian

[Pamphonica]

Ian,
It's certainly a bit strange! I have cleaned the chassis up thoroughly and now to the detective work...
The Field socket is wired to the right places internally, and there is indeed no chance of HT getting to the valves unless somthing bridges this socket. But there's no internal resistor.
However, there is also no sign of any internal speaker being fitted.
And the rear cardboard panel has NO cutout for a field coil plug at all! It is original - all the correct Pam/Pamphonic markings.
I can only assume that the set was always designed for an external simple speaker and that the last repairer removed a series resistor originally fitted internally. He/she certainly did quite a bit of repair. Lots of new resistors, but only one new cap. I have checked all caps and they seem fine so far.
I am sure this is a PAM version of the 15A, not an original Pye. Colour, layout of voltage selector (back panel)

So I am going to fit a 100 ohm resistor across the field socket and carefully wind things up, powering a suitable speaker.

[yestertech]

Hi Jeremy,
I'm certain this must have had a speaker at some point. It would make sense for the rear cover not to facilitate access to the speaker field connections, as they would have been "live" and it may have been possible to damage the set or speaker if incorrect connections were made. The field coil would remain connected but one could still remove the voicecoil plugs for the internal LS and connect an extension unit.
According to the 15 A data, the field coil was 1K ohm, so this may be a better value of resistor to use to complete the HT circuit rather than 100 ohm.

Andy

[Pamphonica]

Hi Andy,
setsappeal to the rescue!
Thanks for the hint - 1K it is, and I'll see how it goes. 1K sounds a lot for a series element - but let's see. Better safe than sorry.
Re the speaker, my analysis is based on the fact that there are no screw holes at all in the rear of the front panel. Really curious.
I have the trader sheet for the 15A, but if you have any more info I would be interested. (The field coil impedance does not seem to be mentioned).
Anyway, thanks for the info. You may recall I have an interest in Pamphonic via my neighbour, the son of the founder of Pamphonic. And from what I hear, Pamphonic was still rather into customisation just after the war, so a speakerless variant is, I suppose, feasible.

Jeremy

[Pamphonica]

Progress:
careful (slow!) power up with a 200 ohm series resistor across the field coil socket and the obligatory mains series bulb showed reasonable currents, a healthy radio and a few stations appearing on MW. Lots of hum though! Current is 60-70mA so a 1000 ohm field winding would need to dissipate nearly 4W!
Replaced resistors with the primary of a small mains transformer (25VA or so) and the hum has reduced to inaudible proportions. Ripple is 4V at rectifier and only 200mV or so after the "choke". Excellent, if not a long-term solution.
A bit of careful IF tweaking livened things up a lot - MW is fairly full of strong stations even on the coil antenna (yes it has one of these, plugged in the side). One IF core has, I suspect dropped off, but the other three are moving nicely and allowed a good maximum. (Hermit3645, is there any easy way to re-attach "dropped" ferrite cores?)
On to remaining alignment.....
A question though - are loudspeakers with field windings now too rare to contemplate?
The 15A circuit diagram shows a loudspeaker with both a field winding and a hum-reduction portion of the voicecoil winding. (This is new territory for me).
(BTW on close inspection there appear to be a few small screw holes that might have held a speaker)
Any suggestions/ sources? I will advertise in parts wanted if you think it's worth doing.
And what size should it be?
regards
Jeremy

[yestertech]

Hi Jeremy
The 1k field coil resistance is stated in the "other components" table in the trader sheet, designated L18.
The HT current appears to be on the high side at 60-70 ma - If the HT voltage is also high that would explain it.
I can probably dig out a suitable 8" 'energised' speaker, which I guess is what would have been fitted originally ?

Andy

[Pamphonica]

Mods, thread has run its course so please close. Thanks