If you have a CCS spec for 100 Watts plate dissip (Pd), then don't list plate
dissipation going up to 500 watts for unprocessed SSB. Unless you are talking
intermittent power to the plate, similar to pulse operation where the peak
dissipation is higher than the CCS #. But to prevent misunderstandings, its
best to not list a peak plate dissipation, instead give a peak output and an
efficiency, from that one can calculate the Pd... I am not certain that voice
on SSB is the same as duty factor of short pulses that is readily calculable.
If the voice peaks are long, then i would think there would be excessive
heating in the anode, if you started out very close to the CCS rating in full
carrier, then switched to SSB. Contact Reid Brandon or George Badger, sometimes
they read this list. Both have extensive experience with CPI/Eimac products. I
am mainly speaking for pulse amplifiers which I work with daily.
John
K5PRO
> Date: Thu, 12 Mar 2009 02:16:41 -0500
> From: Jeff Blaine <keepwalking188@yahoo.com>
> Subject: Re: [Amps] plate dissipation and duty factor
> To: jtml@vla.com
> Cc: amps@contesting.com
> Hi John,
>
> Thanks very much for the info. That's a great bit of data there. And
> it's great to have that confirmation.
>
> For the duty cycle, the ARRL if I remember correctly calls out the duty
> cycles for unprocessed SSB at 20%, and processed SSB as well as
> "conversational" CW both at 40%. And I want to say that PSK runs about
> 70% - something like that.
>
> So to combine all this together, let's say that we have a CCS plate dis
> spec of 100W. And assuming the scaling effect (duty cycle vs plate dis)
> is completely linear, then that means we should be able to safely run at
> these power levels - assuming here that we are only talking about the
> tube to simplify the discussion:
>
> Mode duty cycle plate dis
> --------------------------------------------
> RTTY 100% 100w
> PSK (approx) 70% 140w
> Unprocessed SSB 20% 500w
> Processed SSB/CW 40% 250w
>
> What do you think?
>
> 73/jeff/ac0c
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