[Guest]

I am in the process of completely rebuilding a model 60B radio. My question is about part #8 capacitor, it originally was listed at .18uF but then removed in run number 7 with no replacement but the newer schematic show it was replaced with a .05uF. The model 60B I am using as a reference did not have the .05uF Capacitor. Does any one know if I should add the .05uF capacitor?

Next question is about part #20 capacitor bank, in the radio I am using as reference it appears as if one of capacitors is connected to pin 6 on tube 6A7 which is not what the schematics shows. On the reference radio only one of the .09uF capacitors connects to pin 3 on tube 6A7 and it then daisychains to pin 3 on tube 78, the schematic show each tube gets a .09uF capacitor. Does any one know what is correct? The model 60B I am using as reference is a mid 1936 season radio.

You can check it all out at http://www.heggeseth.com/philco60.asp

[Carl Travis]

What schematic are you using?

[Guest]

I am using the Model 60 (Late) schematic listed on Ron's website.

[Ron Ramirez]

After reading your post it appears to me you have a cross between the "early" and "late" schematics as shown on my website, which is not surprising.

Leave out the extra .05 uF cap. Make sure your resistor (19) is 99K, resistor (24) is 39K, and there is no resistor (22) in your set, but instead, a direct connection between resistors (19) and (24). In which case your set may only have one .09 uF capacitor.

[Guest]

Thanks Ron

As I look in my reference model 60b radio every thing makes sense. It does appear as if one of the 4 capacitors from the capacitor bank [#20] is being used as the capacitor .05uF [#8] although I have now way of knowing what the value is. I would guess it is the other .09uF capacitor. I wonder if this was done to serve as the .05uF [#8] capacitor or if it was a convenient non critical place to terminate the fourth capacitor bank capacitor.

As I have been working on this radio I have tried to figure out all of the various schematics and run updates and it makes me think how these radios were first assembled. It would have been fun to see the Philco factory floor where they were building radios and see how they keep every thing in order.

Brad Heggeseth

[Ron Ramirez]

I spent a little time researching this, and I would now agree that the capacitor in question must surely be .09 uF, instead of a .05 uF capacitor ( 8 ). I'll have to correct my "late" schematic accordingly.

Originally, as you mentioned previously, there was a 0.18 uF cap in that position. Then a 0.2 uF cap was added in parallel with it. Then the connection between the 6A7 and 78 cathodes was removed, necessitating a separate .05 uF cap and 400 ohm resistor between the 78 cathode and ground.

A .05 uF cap between the 6A7 cathode and ground will work. A .09 uf (0.1 uF) will make a better cathode bypass, however.

Gotta love those Philco running changes...

[Guest]

Thanks again Ron,

I will plan to wire up my radio with the .09uF capacitor from part #20 for the 6A7 cathode bypass, and place the other .09uF capacitor from part #20 in-between resistors (19) and (24) as you have described. Another interesting item I found to be forgotten in the schematics is that the suppressor grid for the 78 tube was changed to tie directly to ground. This was listed in a service bulletin and said it was to allow for using European tube 78-E. I have posted what I believe to be an accurate final run schematic for the Philco model 60B on my web site. Please feel free to post in on your site if it looks accurate to you.

http://www.heggeseth.com/philco60_files/Schematic.gif

[Ron Ramirez]

Yes, your schematic is accurate for the final version of Model 60.

About the time we were having this discussion (November 2007), I began to study the various changes made to Model 60. In my spare time, I started putting together a web page which documents all of the changes made to Model 60 during its nearly three year run. That research has now resulted in a new web page on this site. In it you will find every documented change made to Model 60, along with EIGHT different schematics!

http://www.philcoradio.com/tech/60evol.htm

[Ron Ramirez]

Have any of you seen the page on his Model 60 that Brad has posted?
http://www.heggeseth.com/

Very well done...impressive!

It is obvious that Brad has gone to a LOT of trouble to bring his 60 back to life, and has made the chassis look even better than new in the process.

http://www.heggeseth.com/philco60.asp