[Boatanchors] 813 grid to filament short

[Michael Clarson]

On the PEP issue, here is a brain exercise. I know there is a mathematical
basis for PEP, and, that mathematically, 375 watts AM is 1500 watts PEP.
So, lets assume (to simplify the math) that our transmitters are 100%
efficient. On CW, if we output 1500 watts, PEP is 1500 watts, and our 100%
efficient amplifier draws 1500 watts from the power supply. Makes sense.
Now, if we go to AM, and we put out 375 watts 100 % modulated, the RF puts
out 375 watts, and the modulator adds 187.5 watts. Total draw from the
power supply is 562.5 watts, yet produces 1500 watts PEP. The 1500 W PEP on
CW requires 1500 watt dissipation in a dummy load, yet the AM 1500 watt PEP
only requires a 562.5 watt load. Perhaps a single PEP value is not he best
way to specify transmitter power. --73, Mike, WV2ZOW

On Thu, Oct 1, 2015 at 5:16 AM, Rob Atkinson <ranchorobbo at gmail.com> wrote:

> Even though some tube are specified for horizontal operation I avoid
> it with the exception of the small tubes like 6146 and receiving
> tubes.
>
> Large tubes with long grid, cathode, heater leads have to be mounted
> just so, and run within specs, and so on.
>
> I'd reorient the chassis so they are vertical if possible and run them
> and see what happens.
>
>
> > It runs  400W of
> > carrier and 1500W PEP.
> >
>
> I wish AM operators would quit expressing power in therms of PEP, a
> slopbucket term that came about in the 1960s when manufacturers of
> cheap crappy lightweight sweep tube gear etc. designed for slopbucket,
> were seeking to bamboozle appliance operators into thinking they had
> QRO gear ("Up to 2 KW PEP Input!!")  Now, the modern day plastic radio
> operator pisses and moans about how _heavy_ his dinky table top
> leenyar is.
>
> The halfway measurable signal component is the carrier--carrier power
> tells AM operators all they need to know.
>
> 73
>
> Rob
> K5UJ
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