Advice from Scout/Argo 555/556 owners

[Scott Rosenfeld NF3I]

When I crank the volume down to nothing, I get what I can only describe 
as a "whine" out of the speaker or headphones, maybe 500-600 Hz.  When I 
spin the knob (tune the radio) it becomes modulated.

Anyone else see this effect?  Most prominent when listening w/phones.

Still looking for noise blanker and additional modules.  Thanks!

* Scott Rosenfeld NF3I Burtonsville, MD FM19  QRV 80-10/6/2/440 *
*** 6m 64 grids worked on 8 watts ** HF 138 cfmd * QRP-L #147 ***
** QRP ARCI #9054 ** DXCC/WAS/WAC ** 100% dipole powered HF/6m **
* 301-549-1022 h / 301-982-1015 w * 145.490-  147.225+ PL 156.7 *