I am getting ready to align the IF on a 36-650 radio and am a bit confused by the instructions with respect to where the Signal Generator should be connected. The instructions say attach to the Grid Cap of the 6A7 (Det. Osc.) after having removed the Grid clip.
Don't I want to attach the Signal Generator to the Grid clip?
Hi Bill
The cap is on the tube, the clip is the signal input to the tube. If you remove the clip you cut off the radio signals and replace them with the signal generator signal. Radios using single ended tubes instruct us to tune the radio to a quiet place on the dial.
BTW if you need parts for your 650 I have two chassis I'm parting out.
I noticed that the voltages on the Plates of most of the tubes are any where from 50 to 100V higher than the schematic lists.
I also noticed that the Shadow meter is pegged to one side and that there is about 40V across it.
The voltage out of choke (part #79) after the Rectifier (80) is at 303V.
All of the paper and electrolytic caps have been replaced.
Does anyone know if the schematic (attached) is correct?
It could be a resistor issue, there are a couple that seem to be quite a bit out of tolerance.
Any other thoughts are appreciated.
Thanks, Bill
(This post was last modified: 02-13-2024, 12:39 PM by Bill Bacco.)
Your rectifier voltage seems correct as the plates of the output 42s are also listed as 300V.
My guess is you are using a modern DMM to read the voltages, and the listed ones were measured by an ancient analog multimeter with low input resistance (well, compared to a DMM) that would load the circuit and lowered the voltage.
The outputs of the P-P are low impedance, and so is the rectifier, hence correct readings. So it could be OK.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
Some radios call for leaving the clip while others call for removing it.
Following instructions is best as the alignment procedures were performed at the listed setup and changing it might affect results.
In your case, as Rod said.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
Strange enough I went back and did another alignment on the Standard (AM) band and now the voltages are a bit lower and the voltage across the Shadow meter is much better. Around 4-6 volts depending on the tuning, as you would expect.
Not sure what I did.
The radio has been playing all along, since I recapped it. Just trying to get it pulling in stations better and clearer.
Bill, I merged your two 36-650 threads into a single thread newly titled, 36-650 restoration to keep the discussion on your set all in one place. It makes it easier to follow and more complete when folks look at it in the future. Thanks.
