[AMRadio] Safe Metering for Blind Operators

Edward B Richards zuu6k at juno.com
Mon Jan 3 14:50:38 EST 2005

Hi Mike;

I have a Heathkit DX-100B. The plate meter is across a .1 ohm resistor
from the center tap of the HV transformer to ground. This should serve
your needs. Good luck.

73, Ed Richards K6UUZ

On Mon, 3 Jan 2005 12:43:25 -0600 "Mike Duke, K5XU" <k5xu at jam.rr.com>
> K4KYV wrote:
> "In my homebrew rigs with triode finals, I place the plate meters 
> between 
> the
> common point for grid leak/bias supply and PA filament, and ground.  
> The
> Gates BC1-T does it the same way, with no HV on the meter."
> I've been reading the discussion of safe metering with great 
> interest, as 
> perhaps explained by my subject line and signature.
> I would love to find a good plate modulated transmitter in the power 
> class 
> of a DX100 or Valiant, in which the plate meter would not have the 
> full 
> plate voltage across its terminals. Is anyone aware of a commercial 
> or 
> surplus transmitter with this design feature?
> I could easily and safely tune such a transmitter by connecting an 
> audible 
> meter-reading device across the meter terminals. I still have the 
> circuit 
> which I used successfully with a DX60, and very cautiously with a 
> Viking 
> Ranger from 1969 - 1974. I learned quickly that the ranger meter is 
> at full 
> plate potential. The good news is that I lived to tell about the 
> experience.
> I also recall reading somewhere of using a voltage divider in order 
> to 
> obtain a safe potential level in the external audible reader. If 
> anyone on 
> this list has ever encountered a transmitter which was modified in 
> this way, 
> I'd like to know more about how it was done, since I'd love to put a 
> Ranger 
> on the air in order to re-create my first station.
> The point can be made that the easiest route is to put a rice box 
> and linear 
> combination on the air. Yes, that would be the easiest thing for 
> anyone, 
> but, not nearly as much fun!
> Mike Duke, K5XU
> American Council of Blind Radio Amateurs
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