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52-542 problem - Printable Version

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52-542 problem - tab10672 - 07-30-2014

I am working on a 52-542 and after checking all tubes, coils and full recap I started alignment, first part was fine, adjusted all 4 slugs to 455 loud and clear signal but when i tried the ant./osc. at 1600 through a loop as per instructions I get nothing no matter what or where anything is adjusted. Through the antenna there is nothing but static across the dial. I have checked and rechecked everything but can not find any problems. Any suggestions would be appreciated.
Thanks, Todd
http://www.nostalgiaair.org/PagesByModel/741/M0013741.pdf

RE: 52-542 problem - Steve Davis - 07-30-2014

Have you checked to see if the oscillator is working?

Steve

RE: 52-542 problem - tab10672 - 07-30-2014

Voltages check ok, even replaced the osc tube with a known good tube.

RE: 52-542 problem - tab10672 - 07-30-2014

I just checked it through a transistor radio for osc, and no it is not but again i cant find any reason why it shouldnt.

RE: 52-542 problem - PAradiogeek - 08-01-2014

Try doing the initial adjustment at 1500 instead of 1600. If the dial/oscillator tracking is off on the set, you may not have the 'range' you need to align all the way at the top of the scale. Doing it at 1500 will give you a little more room.

GL,
Jon

RE: 52-542 problem - tab10672 - 08-01-2014

It won't pick the gen up anywhere except 455. I have no idea what else to look for, all voltages are correct, tubes good, coils good, tuning cond good, all caps and resistors are good. The only thing I haven't checked is the loop antenna but even if it were shorted somewhere wouldn't it still pick up a signal through my dummy loop on the gen?

RE: 52-542 problem - PAradiogeek - 08-01-2014

Is the loop antenna installed? If the loop antenna had a break in it, it might prevent reception. Try ohming that out. Should be very low ohms.

You say the coils are good. Does this include the oscillator coils (T1)?

You could try injecting the RF directly to the 7A8 grid (through a .1 uF cap). If that works, the problem is most likely with the loop antenna.

RE: 52-542 problem - PAradiogeek - 08-01-2014

Did you test the 7A8 tube? Did you try another one (even if the first one tested OK)? In my (limited) experience I have found (and read) that converter tubes are rather finicky.
Edit: Sorry, missed the post near the beginning where you said you tried that.

RE: 52-542 problem - Radioroslyn - 08-02-2014

Check pin 4 of the 7A8 with a VTVM. Should read a small - voltage there like -1 to -3vdc. Also check for the 105vdc on pin 3. If not your osc is not working. Check T1 for open windings, open cathode resistor, or bad 47mmfd mica.
GL
Terry