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

[Kenneth G. Gordon]

On 11 Feb 2013 at 4:31, Mike Everette wrote:

>  I have never in my entire 56 years in electronics
> > ever run across 
> > anything as microphonic as this thing is.
> 
> Hallicrafters SX-96!!!!

Ah, yes. Happy Crappers.
 
> 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.

That is exactly what this one is doing. If I put the speaker anywhere near the 
thing, it starts to howl, and it builds up to a shriek.

> 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.  

Did that once. I'll do it again....after I have carefully examined the IF cans.

> 
> 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.

Did that twice so far.

> 
> 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.

No inductor switches in this thing, but tube sockets. I'll clean them one more 
time.

Thanks, Mike.

Ken W7EKB