[Amps] 4pr1000 bias question

[jeremy-ca]

----- Original Message ----- 
From: "k7fm" <k7fm at teleport.com>
To: "jeremy-ca" <km1h at jeremy.mv.com>; <andy at gd0tep.com>; "'amps'" 
<amps at contesting.com>
Sent: Wednesday, April 02, 2008 11:10 PM
Subject: Re: [Amps] 4pr1000 bias question


> "Thats 1200W idle current for AB2!
>
> Eimac recommends around 500-600W. Are you looking at the PP pair AM
> modulator spec?"
>
> I suppose the good news is that someone reads the stuff I write.  I should 
> waht I send out, since 1200 watts indeed exceeds the plate dissipation of 
> the 4-1000.  I can plead that I was simply a scrivener, reporting the 
> facts typed out in the 1972 Radio Amateur's Handbook.  There are 
> footnotes, but none apply to the data quoted.  So, nothing says two tubes, 
> but it would have to be.  However, with Carl's data and mine, it appears 
> that the original question can be answered.  Bias voltage should be 
> around -60 volts and would then be set for 150 ma, which is the 600 watts 
> Carl mentioned. The -200 volts on cw would be cutoff (or it could be 
> higher) on standby.
>
> Less plate voltage will require less negative voltage to set the proper 
> bias.   Old tubes may require less negative voltage.
>
> Good catch Carl!  Wonder why the ARRL is giving us data for a 3 KW 
> modulator, and where is the 6 KW am rig construction article.

I would have buzzed right buy it except having built many one and two holers 
for customers in the days good pulls were freebies 2 or 4 at a time from 
local 5KW BCB rigs.

The 2 holer articles were in the W6SAI books until they got pressured to 
stop.

Carl
KM1H


> 73,  Colin  K7FM
>