[morzh]

well, I got this Halson chassis from Kirk Saturday. Yesterday, Monday it sang.
Pull the local station pretty well.
Did not do much - Kirk recaped it, so I simply checked the coils etc, checked the electrolytics (to the possible exent, not gonna open the can again).
Kirk did good recapping, I only replaced the line filter cap with Y-cap.

Radio sang with shield off. With shield on it played quietly, which is no wonder as the antenna wire was not there.

The volume pot is a bit scratchy...the pot is not easily disassembled. And it is a repacement pot.

There s one weak tube, 57.

The lineup is 57-58-47 and 80 rectifier (AC set).
I found Halson 515 which is, though having some other tubes, is very similar and so I used it as a reference for power and output hookup which are very much same.

Now, eventually when it pulled in station, I started looking for alignment....well, guess what. It got no pods.

It is, as it sees, a TRF.
57 and 58 first implied there might be a det-osc and so it would be a superhet, but no - it is a TRF and with no pods at that.

I can see bent outer leaves on the tuning cap, I guess this is the alignment.
Well, I am not going to disturb it.

Done.

Kirk, you will need a good antenna with it, it is not an overly senitive set.
And if possible you could try a good 57 tube.

[Mondial]

Morzh, are the tubes in the right sockets? Lineup of 57, 58, 47, 80 implies the wrong order.

If its a TRF, 58 should be the RF tube and 57 the detector.

[morzh]

Yes they are. I did not watch the order when I wrote, but the tubes names are on the sockets - hard to miss.
But you are right , I think 58 is before 57.

In superhets it could be otherwise.
57 is DO, then 58 is IF. (american Bosch 305)

[OldRestorer]

Very interesting, don't know what it means yet but it works!
Dumb question... Where does the antenna connect?
I have always had one attached so I never followed the wire.
I have another 57 in a box so I hope it is good.
Someone offered a Eico 666 but disappeared

Great job Mike! Better be

Kirk

[morzh]

Kirk

There was no antenna wire in there at all.

In those TRF types it usually attached to the point where the volume pot meets the top part of the antenna coil.
This is where I put it. I soldered a wire and put it through that hole in the chassis, that obviously was used for that.

http://www.nostalgiaair.org/PagesByModel...013881.pdf
(at the very last sch, 2x47 tube output one, at the p13, look at the vol. pot's #1 wiper and #2 coil).
http://www.nostalgiaair.org/PagesByModel...008947.pdf
(look at the item 7 and coil 32)

[morzh]

Remember those two wires Kirk got zapped with?

It just dawned upon me: I think, someone was trying to make a tone control switch.

Here's the rational: both wires came from the primary of the output transformer.
I also realized the usual capacitor placed across it in Halson design is missing (of course I cannot prove it was there in the first place, but then identical Halson output solutions all have about 6nF cap across the primary).
And, although we are accustomed to see the tone control cap swutches from the anode to ground, it does not really make any difference if the switch is in between the anode and the B+, as for the AC B+ and GND are more or less the same. Which is where the primary is connected.

So maybe that what it was, that zapped Kirk.

PS. Maybe I should put a cap in parallel - it does sound a bit high-pitch to me.

[jerryhawthorne]

Nice to see you Mike and Kirk working together with each you own talents. Nice "marriage".
I have friend in New Mexico that does great cabinet work and now has my Fada, I have helped him on some chassis but he is now working those on his own.
Jerry