[ARC5] 10 meter BC-454 - more yet.

[Mike Everette]

--- On Mon, 2/11/13, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:

 
 I have never in my entire 56 years in electronics
> ever run across 
> anything as microphonic as this thing is.
> 

Hallicrafters SX-96!!!!

I had one that if a fly landed on it, the sound was akin to a B-52 touching down... if someone knocked on the front door (my shack was in the back of the house), I swear, it came through the speaker.  If the audio gain was turned way up with only rush-noise coming through on 15 or 10 meters, the radio would howl like a banshee.

Also the old Narco VHT-2 and VHT-3 tube type NavCom transceivers used in light aircraft.  They would get so noisy and microphonic after only a few hours in the air that they were unusable.

If you haven't already done so, clean the tube socket pins and the tube pins themselves.  

Clean the wipers on the variable condenser rotors, if you haven't done this.  I would also clean the coil pins really well if you have not yet.

The aforementioned Narco radios had what was called a "step inductor" for tuning.  It was very much like the rotary contact of a selector switch.  Oxidation on the step inductors was the Number One cause of microphonics in the radio.  Tube sockets were a close second.

73

Mike
W4DSE