[Heathkit] HW-16 hum

[Kevin Ward]

This sounds a bit like the hum problems we have with direct conversion
receivers.  Try a .01uF capacitor across each diode and one across the power
supply electrolytic filter capacitor(s).  Those spikes are short rise-time
events.  Think of them as a high-frequency component superimposed on the DC.
The electrolytics have a very poor response to that.  Any good regulated
low-voltage power supply has a small value capacitor connected across the
terminals of the electrolytics to keep this stuff out of the regulator, a
high gain device.  You want to keep it out of the audio chain, also high
gain.

Kevin  N2IE



-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.394 / Virus Database: 268.9.7/379 - Release Date: 6/29/06