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GE Model 210 AM Sensitivity
#1

I'm continuiong the discussion on the GE 210 from the "August Finds and Losses" to here where it is probably more appropriate.  Mr. Fixr, I have done the resistance measurements for the first and second AM IF transformers.  They conform to the given values of 15 ohms on both the primaries and secondaries.  I recleaned the band switch and measured the continuity thereof and contact is securely made, both AM and FM.  I found a connection from the Variable cap to the antenna that was loose and I re-soldered.  Very little change in sensitivity.  I will probably look at performing an alignment tomorrow.  I rarely align a radio if the tracking is only off a little, but that seems to be the next step.  Thanks to all who have contributed to finding an answer to this problem.  Joe

Courage will follow when Faith takes the lead.
#2

I aligned the radio after church this afternoon.  I was hoping that someone had taken a screwdriver and 'adjusted' all the twisty things.  No change to sensitivity.  The radio will now join my others on display.  It's still a handsome radio.  Thanks to everyone who showed encouragement.  Joe

Courage will follow when Faith takes the lead.
#3

Are you sure you are not citing the wrong model number, the G.E 201 seems to be a single band AM only radio with trimmer tuned IF cans, not slug tuned? This is the one that comes up as a model 201 https://www.radiomuseum.org/r/general_el_201.html https://www.tuberadioland.com/ge200_and_201_main.html
Regards
Arran
#4

I’m guessing this is the schematic for your radio, a model 210.

GE 210

Looks like a slug tuned IF set.

Tony

“People may not remember how fast you did a job, but they will remember how well you did it”
#5

Tony, Yes, that's the one. As I mentioned previously, and per recommendations, I've measured the resistance of the primary and secondary of both AM IF's and they are supposed to be 15 ohms, and they measured between 15 and 16 ohms. I've tapped the cans to see if there is anything to cause noise, I've seen no electrical arcing, and I've aligned the stinker. I've checked each connection for cold/loose solder joints. No joy. Do you have any ideas? Thanks, Joe

PS: I haven't checked the Mica caps; I will do that now.

Courage will follow when Faith takes the lead.
#6

There are seven 47mmf (.047nf) Mica's in the circuit. My LC1020E LCR meter measures them as follows: 5.4nf, 1.03nf, 1.33nf, 2.57nf, 3.4nf, 4.7nf, and .059nf.  That last one is the only one within tolerance.  I bought six when I purchased the tubes from Jim Cross at VTI.  I am going to now replace them one-by-one beginning with the most ouit of spec on down and see what, if any, difference that makes.  Stay tuned.  Icon_e_smile  Joe

Courage will follow when Faith takes the lead.
#7

That should be interesting. It's not common to see mica caps increase in value. Could be a bad lot. I wonder if they may have contamination of some kind.
#8

Rod,  The problem is UE, User Error! I tested the caps in-circuit.  Out of circuit they are within tolerance.  So back they went.  My last straw is the attached schematic


   
L10, C1B, R31, C11, and the band switch appear to be soldered at BOTH ends to ground!  The band switch is connected via a copper strap to one end.  I just can't believe that GE would have done this, or that it would have passed QC.  MrFixr told me to look at the band switch  Icon_redface and I swear that I did the continuity checks.

   

What do you think? I can separate the components, but is this how that circuit should be?   My head aches!!  Thanks all!  Joe

Courage will follow when Faith takes the lead.
#9

The caps inside the AM IF transformers would be hard to measure as they are across the windings, you would have to remove them to measure, which means taking the transformers out, and apart. I'm pretty sure that one or more of tie mica caps in those transformers might be open if adjusting the slugs doesn't do anything to the gain. I have an older AM/FM radio that has the opposite problem, the AM side is fine, but the FM is deaf, only picks up the two strong local stations, and rather weakly, the tubes are fine, tested those, it could be the electrolytic for the ratio detector but maybe not, so on the shelf it sits.
Regards
Arran
#10

Thank you Arran.  When I measured the IF cans, it was for the coil resistance.  As such they were 15-16 ohms, schematic shows 15 ohms for their value.  I'm going to button this one up and call it a day.  I may come back to it in the winter and rip open the IF cans.  For now, I have more radios to work on, including a Canadian Philco model 81 Transitone.  Cheers,  Joe

Courage will follow when Faith takes the lead.




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