[37silverstreak]

Hey everyone,
I've been working on this 40-150 for a couple of weeks. I've replaced all the caps and most of the resistors. the ones I left were all within 10% tolerance. I have also replaced all of that wonderful rubber coated wire! I brought up the set on my variac with no nasty surprises I'm getting static but no stations as of yet. The amp side seems to be working fine. I can vary the volume and tone. also when I hook up my signal generator I can pass the 455kc IF signal loud and clear, just can't pull in any stations or signals from the generator. I'm thinking maybe oscillator trouble? Any one have any pointers or ideas where I should start?
The mystery I have with this set is with the detector/ oscillator tube. The Rider schematic shows that this tube should be a 7J7 loktal tube for the 40-150 series. My 40-150 has a 6J8G tube in it's place, so I'm a little confused! Is this an early production set that Philco changed the design during the run? It's original to the chassis and no ones modification. Also the chassis is clearly stamped 40-150 code 121. I'm stumped, so any ideas would be great! Thanks!
Kevin

[Ron Ramirez]

I don't think the code number ever changed in production of the 40-150 and 40-155, but yes, the oscillator tube changed - not once, but twice.

Originally these used a 7J7. Then Philco switched to a 6J8G. Later on, they switched back to a 7J7. Same applies to the 40-180, 185, and 190.

If you look in a tube data book or online such as here:
http://www.nj7p.info/Common/Tube/SQL/Tube.php

you will see that the 7J7 and 6J8G are essentially identical electrically, but one is loctal and one is octal with a grid cap, and the pinouts (and sockets) are different.

Beware the oscillator tube socket in these models. It is made of that light tan material that is very delicate, very fragile, and very prone to failure, breakage, etc. I don't know why Philco did that, maybe that stuff is a low loss material compared to the normal brown wafer used in other sockets? I've replaced these with brown wafer sockets from junk Philco sets and did not have any problems afterwards.

[37silverstreak]

Thanks for the info Ron! Ironically, I've already found out just how fragile that tube socket is! Fortunately I was able to carefully epoxy the pin back in. I will take your advise and replace it with another octal socket just as soon as I dig up a replacement.
Kevin

[DeckApe]

Kevin--

I broke the same socket in my 40-190. I did JB-Weld mine back together, but it was unable to withstand the soldering heat. Save yourself some grief... get a new socket. (Fortunately, I used my socket problem as an excuse to run up to SPARK! Museum of Radio & Electricity in Bellingham, WA, just an hour away.)