[Heathkit] HW-16 Warble

[Glen Zook]

Since the warble appeared with just the HG-10 in the "spot" mode, I would look very closely at the HG-10.


Are you powering the HG-10 from the unit or using a separate power supply?  If you read the HG-10 manual very close, you will see that Heath really recommends running the VFO from a separate, regulated, power supply.  Doing so eliminates a lot of problems.


Also, it is best to run the VFO constantly when in transmit instead of keying the VFO along with the transmitter.  This is true with all of the external VFOs.

 Glen, K9STH 
Website:  http://k9sth.net


      From: Rodger Singley <wq9nsc at live.com>
 To: Mark K3MSB <mark.k3msb at gmail.com>; Heathkit List <heathkit at mailman.qth.net> 
 Sent: Wednesday, August 17, 2016 9:01 AM
 Subject: Re: [Heathkit] HW-16 Warble
   
Mark,



That is a pretty bad chirp in the recorded audio you uploaded.  Coupled with your finding that it shows up on the receive side with the audio output increased it certainly sounds like a B+ issue and is sufficiently bad that the VR tube in the HG-10 cannot compensate for it.  If the problem was only on transmit I would suspect an issue with an aging VR tube in the HG-10 but since it shows up on both either the power supply itself or something creating an unusual load on it is at fault and the problem on both transmit and receive (at higher audio loading) points to the problem being in the supply itself.



Although power supply regulation issues are usually fairly easy to find this isn’t always the case and a standard scope setup will sometimes fail to catch little variations.  Since this is likely a voltage change/regulation issue you will need to set the scope input to DC coupled but then most scopes aren’t sensitive to a small change because the base DC level “swamps” the variation.  I use a Tektronix 7A13 differential comparator plug-in with my 7854 mainframe and this plug-in has built-in adjustable DC offset so that you can cancel out the main DC input voltage and leave the plug-in set for high sensitivity to display minor variations in voltage.