[bridkarl]

All recapped and checked. Had to order a new knob. Seems to work ok.

The bulb seems to be an issue. It’s bright for a moment and then gets truly dim. Seems to be drawing too much B+. I haven’t replaced any tubes so that may be the issue.

 I also couldn’t figure out if the original power cord went under OR through the antenna. I put it under using a polarized cord with the hot side to the switch. I’m debating if it needs a fuse, but since I use it through a fused isolation transformer I think not.

 
   

[jrblasde]

Fantastic progress so far! You bring up an interesting question regarding fusing. I don’t hear much about people fusing transformer less AC/DC sets. Maybe I just haven’t happened to catch those particular conversations, I don’t know. But I’ve long wondered. 

Does the bulb remain bright if you pull the 35Z3 tube? You won’t get any plate voltage if you remove this tube, but the rectifier is really the only thing I can imagine would suddenly dim the bulb, once it heats up and starts rectification.

[bridkarl]

   

the bulb is acting as a current limiter. Sort of a cheap solution to save the rectifer and the power supply filter. I’m thinking there’s some better solution.

I’ve used an inline fuse in the hot side of the switch before. Not sure it’s worth it given there’s a fuse on my isolation transformer, but if they have one at Ace Hardware next time I’m there…

Not sure what else this needs aside from an alignment. I haven’t swapped out tubes yet

[Arran]

I have heard of some people adding current limiting resistors ahead of the heater string in AC/DC sets but I never bothered, I don't use most of them enough to blow out tubes anyhow. The last tube I had fail was after the radio had been on for an hour, and it wasn't even at one end of the heater chain, nor did it go open until after I tried checking it in a tube tester. There were a lot of dodgy components used in post war sets, and this one was from 1947-48, including tubes sometimes, I think the PT6 was a 1940 model was it not? I like the design of the cabinet by the way, clean yet elegant.
Regards
Arran

[bridkarl]

It’s a 1941 model. I won’t be using it enough to justify figuring out.
All that’s left is getting the knob I have on order and figuring out what size screws I need to hold the chassis in the case.
I suppose a thermistor in series with the bulb might work but what value??

[462ron]

I don’t know exactly how dim your pilot gets but this is the typical of the response of many transformerless AA5s where the bulb, usually a #47, is in series with the filament string and across a portion of the rectifier filament and plate of the rectifier. When first switched on, the filaments are cold, thus at a low resistance for a bit. The bulb flares up bright but then dims down as the filaments heat up and increase in resistance. Then the tubes start to conduct and draw current through the rectifier and the bulb so the brightness comes up slowly. From what I’ve seen, it doesn’t get as bright as it does when first switched on and filaments are cold.

Ron

[jrblasde]

I agree with Ron. That’s how my 49-906 behaves. That’s why I’m curious if the bulb stays at full brightness if the rectifier tube is pulled.

[bridkarl]

I’ll get on doing that and see what happens.
Just to keep this all in one thread -

Anyone know what length/size is used for the screw holding the chassis on And any recommendations for touch up paint for the black trim? I have several Philcos with that black edging.