The PHILCO Phorum
Alignment question - Printable Version

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Alignment question - ODPILOT - 10-05-2014

I restored a 53-1750 radio phonograph - all new caps, resistors and replaced any bad tubes.   The radio picks up the AM stations but only fairly weak.  The phonograph works great.    I don't seem to be able to align it with my signal generator.  I tried hooking in the signal generator directly into the radio as per the schematic instructions and I've tried to put the output wire near the radio's antenna and I get no signal coming through the radio when the generator is set to 455 KHz. 
      I know the signal generator works and it's signal output is very precise,  because if I set it for any regular AM channel - I can hear the signal no problem -  i.e.  if I set for 750 KHz AM -  it comes in loud and clear with the radio set to 750 am.   So my question is - can't I just set the signal generator to any  regular am station (rather than 455 KHz) and turn the little scews in the low frequency "coils" so that the regular am stations will come in as strong as possible??  [Image: http://philcoradio.com/phorum/images/smilies/icon_problem.gif]
      

RE: Alignment question - morzh - 10-05-2014

Have you checked ALL yor coils for continuity?

RE: Alignment question - ODPILOT - 10-05-2014

Not sure I know how to check the coils for continuity.  However, I messed with it after I wrote the above post.  I thought that the coaxial cable that is screwed into the "RF Out" of the signal generator would act like an antenna.  It does not.
When I bring the entire signal generator next to the antenna in the Philco radio,  I then hear the signal MUCH louder.  Maybe I'll try it again with the 455 KHz method and see if that works better now that I know the RF signal comes out of the actual signal generator unit better than the coaxial cable I was trying to use like an antenna. 
        

RE: Alignment question - Warren - 10-06-2014

You can make a small antenna to hook upnto the sg easily. I put two small boards together like an x then wrapped wire around it about 6 to 8 times. Hook the two ends to the sg and it should put out a signal for your radio.

RE: Alignment question - Mondial - 10-06-2014

It will be hard to radiate a 455 kHz signal to the radio, because the front end tuned circuit rejects it. You can try it, but unless the IF signal is very, very strong. It will not get past the antenna tuned circuit. The usual procedure is to directly inject the IF signal into the converter grid circuit through a coupling cap. You can usually access this point at the antenna section terminal of the tuning cap

RE: Alignment question - ODPILOT - 10-06-2014

WARREN -  The signal generator I have has a coaxial cable connected to the RF out and the cable has an alligator clip on the end.  If I make my own antenna,  I hook both ends of the wires to the alligator clip  OR one end to the alligator clip, and the other to what ? 

MONDIAL -  If I "inject" the signal from the generator directly into the antenna section of the radio with a capactor in the line,  will that do it - or is there a ground and/or another part of the signal generator that needs to be attached to a ground in the radio as well?

Thanks

RE: Alignment question - codefox1 - 10-06-2014

Agree, for I.F. alignment, follow instructions, for RF (on AM,), I have an tp cardboard with about 25 turns of magnet wire that I couple to signal generator and place near the radio, seems to work OK. I also do check and adjust accuracy of what my ancient signal generator spews forth, after it has warmed up, with a frequency counter. If you don't have one, very inexpensive little digital ones are available, and are pretty accurate.

RE: Alignment question - Warren - 10-06-2014

I connected one end of the home made ant to the ground from the sg and the other end to the output of the sg. Then I got a signal.