HW-12A Issues

[RAY FRIESS]

I am in the process of cleaning out the shack and will have an HW 12 or 22 rig for sale.  It is missing it's function switch, but otherwise is all there.  If anyone is interested, let me know...
Ray  wa7itz
  ----- Original Message ----- 
  From: ve3fwf<mailto:ve3fwf at SYMPATICO.CA> 
  To: HEATH at LISTSERV.TEMPE.GOV<mailto:HEATH at LISTSERV.TEMPE.GOV> 
  Sent: Wednesday, February 14, 2007 6:04 PM
  Subject: Re: HW-12A Issues


  Kent:

  There is no service manual per se other than service bulletins.

  Based on your E-mail, I assume that the receiver is working just fine.  So 
  try the following:

  1. Check for B+ . You can do this from the top of chassis near the left 
  front where the RF choke resides. Careful here, 800V !  Make sure that the 
  power supply is not sagging under load. You may have bad electrolytics in 
  the power supply.
  2. Also check the screen voltage. Best to use the voltage reference table in 
  the manual at this point and check all voltages around the finals and the 
  driver both in RX and TX mode.
  3. If 1. and 2. are OK, swap the TX mixer tube with another similar tube in 
  the radio.
  4. If still no joy, then I would use a scope and find out where the RF is 
  falling off. You should have about 50 volts PP on the grids of the finals. 
  There are some signal levels in the manual.


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