[BC] CCA AM tips

[Bob Groome]

Unable to modulate over 15%.....
  Is the PA efficiency around 77 to 82%. It should be close to that; if  lower more power from the modulators is needed than can be created.
  Static modulator currents should be balanced. Yours show un-blalnced;  could swap the modulator tubes to see if problem is bad tube, bad  socket/other problem.
  Bias supply for modulators OK voltage wise?
  If it ain't tubes, sockets, feed back resistors/caps; then you need to look at the modulation iron and coupling cap.
  These are pretty easy boxes to trouble shoot. You do have a schematic?  V & J (look in Radio Guide or Radio World for phone number)   has parts for these old tanks.

Larry Broome <larry at rjbbroadcast.com> wrote:  A couple of things to note about that CCA transmitter;
     
1. it goes through sockets faster than most, might want to check the actual socket itself and make sure making good contact.
2.  althought the transmitter is built like a "tank", it was poorly  designed regarding cooling and air flow. While you are doing work on it  invest in a larger internal fan and make sure in a well circulated  location.

Hope this helps!

Larry Broome
RJB Broadcast Corp.


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Bob Groome 
An apology is the 'superglue' of life. It can repair just about anything.                                       Lyndon Johnson

Home address is bobgroome at yahoo.com
Work address is bobg at jampro.com
Web: www.Jampro.com
at Jampro Antennas, Tel: 916-383-1177 Building TV & FM antennas for 50 years
		
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