[ARC5] On Hacking

[Mike Hanz]

Those are valid points, John, _*/if/*_ the set was operated within its 
standard voltage and current design envelope.  Unfortunately, some hams 
wanted a lot more power out of them, using plate voltages that exceeded 
the published 600v maximum by significant margins.  That kind of 
mistreatment drives a healthy increase in harmonic distortion.  I have a 
couple of examples here given to me by a very smart NRL RF engineer that 
has the usual screen wire, bypassed power and control leads, and an 
added capacitor to complete the pi matching network into a 50 ohm 
resistive antenna load.  He claimed he was getting close to 100 watts 
out of those little boxes.  I'm not sure how he was cooling them...he 
must have used a blower hung on the side of the tube compartment.  I 
don't see how he could have obtained any appreciable life out of the 
tubes at that level without forced cooling.  But then again, 1625s were, 
what...a quarter apiece?

  - Mike  KC4TOS

On 10/16/2012 1:40 PM, J. Forster wrote:
> I was waiting for that canard.
>
> The TVI rep was fror two reasons:
>
> 1. Ham gear manufacturers condemned the ARC-5 and similar sets to sell
> their hardware.
>
> and
>
> 2. The ARC-5, and many other similar vehicular transmitters, had
> electrically short antennas and these were resonated by the output
> (variable) inductors in the sets. This was a high-Q circuit, so would kill
> harmonics well.
>
> Any time I see an ARC-5 with a SO-239, I know it belonged to a ham with
> little to no understanding of its proper operation.
>
> -John
>
> ================
>
>> One might forget the TVI "improvements" that were necessary, especially in
>> urban and suburban locations, to keep one's neighbors from storming the
>> castle like was done to Doctor Frakenstein!