I have noticed that on some philco schematics that the resistance values for the same components (2nd IF #32-2102) is different. For the model 37-610 the primary resistance is 1.5 and secondary is 77ohms, on a Philco 37-38, the same part# is 77ohms on the primary and 7ohms on the secondary. Whats the deal?

Dave

Those values are just there for checking with an ohm meter. They don't indicate IF Transformer impedance. Size of wire will make a difference.

My book lists primary as 11 and secondary as 7 ohms for 37-38. It shows 11.5 and 7.5 for 610. At least this book has close readings.

Wonder if 1.5 should be 7.5 ohms? Could 77 actually be 11?

Norm

:I have noticed that on some philco schematics that the resistance values for the same components (2nd IF #32-2102) is different. For the model 37-610 the primary resistance is 1.5 and secondary is 77ohms, on a Philco 37-38, the same part# is 77ohms on the primary and 7ohms on the secondary. Whats the deal?

Dave, have you measured the winding resistance of your xfmr? I think the winding resistance is given just to verify that the xfmr isn't open - if it's not open, then it's probably OK?

If I remember correctly, the Philco 610 is one of those "cake box"-style chassis, aka "unit construction," and aka "the chassis from hell." I was nearly driven insane trying to work on one of those. Is that yours?
Doug

:Dave
:
: Those values are just there for checking with an ohm meter. They don't indicate IF Transformer impedance. Size of wire will make a difference.
:
: My book lists primary as 11 and secondary as 7 ohms for 37-38. It shows 11.5 and 7.5 for 610. At least this book has close readings.
:
: Wonder if 1.5 should be 7.5 ohms? Could 77 actually be 11?
:
:Norm
:
::I have noticed that on some philco schematics that the resistance values for the same components (2nd IF #32-2102) is different. For the model 37-610 the primary resistance is 1.5 and secondary is 77ohms, on a Philco 37-38, the same part# is 77ohms on the primary and 7ohms on the secondary. Whats the deal?

Doug, not sure what you mean by cake box, it has a separate rubber isolated center section. Most of these radios are kind hellish to work on but not too bad. Norm, I believe the 11 is actually 77ohms. The primary side was open. I was able to solder a small wire across a coil to get 80 ohms on the primary. Put it on a scope and sig. gen. and it seems to peek the amplitude ok and keep the freq.

Dave

As long as you have continuity should be ok. Looks like 11 ohms here but "1" and "7" are almost the same in this schematic.

http://www.nostalgiaair.org/PagesByModel/204/M0013204.pdf

This one has to be wrong. No way would one be 1.5 ohms and the other 77 ohms.

http://www.nostalgiaair.org/PagesByModel/209/M0013209.pdf

Here is the same radio from 1936. These numbers look good.

http://www.nostalgiaair.org/PagesByModel/797/M0013797.pdf

Norm

:Doug, not sure what you mean by cake box, it has a separate rubber isolated center section. Most of these radios are kind hellish to work on but not too bad. Norm, I believe the 11 is actually 77ohms. The primary side was open. I was able to solder a small wire across a coil to get 80 ohms on the primary. Put it on a scope and sig. gen. and it seems to peek the amplitude ok and keep the freq.

Dave

Since the primary is open solder a 22K across this winding. The numbers we are reading on the schematic are DC ohms. This has nothing to do with impedance. Then connect a 100 pf cap between plate of the IF tube and secondary of the IF Transformer. Radio will work almost as good as new.

Norm

:Dave
:
: As long as you have continuity should be ok. Looks like 11 ohms here but "1" and "7" are almost the same in this schematic.
:
:http://www.nostalgiaair.org/PagesByModel/204/M0013204.pdf
:
: This one has to be wrong. No way would one be 1.5 ohms and the other 77 ohms.
:
:http://www.nostalgiaair.org/PagesByModel/209/M0013209.pdf
:
: Here is the same radio from 1936. These numbers look good.
:
:http://www.nostalgiaair.org/PagesByModel/797/M0013797.pdf
:
:Norm
:
::Doug, not sure what you mean by cake box, it has a separate rubber isolated center section. Most of these radios are kind hellish to work on but not too bad. Norm, I believe the 11 is actually 77ohms. The primary side was open. I was able to solder a small wire across a coil to get 80 ohms on the primary. Put it on a scope and sig. gen. and it seems to peek the amplitude ok and keep the freq.