The AL-1200's Ive had thru here wont do much over 1700-1800W at 100W drive.
They wake up at 125-150W and can equal the AL-1500 at 80-100W.
Carl
----- Original Message -----
From: "Bill, W6WRT" <dezrat1242@yahoo.com>
To: "Amps reflector" <amps@contesting.com>
Sent: Thursday, July 02, 2009 1:46 PM
Subject: Re: [Amps] AL1200/RTTY
> ORIGINAL MESSAGE:
>
> On Thu, 02 Jul 2009 08:28:40 -0700, Kevin Normoyle
> <knormoyle@surfnetusa.com>
> wrote:
>
>>
>>Hey Bill: it does raise the question: When your coil blew, how did you
>>know you were running 1500W?
>>If the AL1200 was underreporting (like mine might be), then maybe you
>>were over 1500W??
>
> REPLY:
>
> That was enough years ago that I can't honestly remember, but I was
> probably
> using a Kenwood SWR/Power meter at the time.
>
> In any event, since I know power meters are notoriously inaccurate as well
> as
> frequency-dependent I always tune up by peaking the tune and load caps for
> max
> output, while limiting the DC plate current to a specific value by
> adjusting the
> amount of drive. For example, I now use both a Bird 43 and a Palstar
> PM2000A.
> They agree pretty well on 20 meters and a bit less well on other bands. I
> find
> my amp puts out exactly 1500 watts on 20 meters when peaked up and with DC
> plate
> current of 800 mA at 2900 VDC. So on other bands, I tune for max output
> with 800
> mA DC and let the output fall where it may. I get a variation of about 50
> watts
> from band to band with the Bird, somewhat more variation with the Palstar.
>
> I also monitor the blower exhaust temperature to be sure the tube is happy
> on
> all bands, which it is. My blower is a 91 CFM model which is overkill for
> a
> single 8877, so the output temp never goes over about 140 degrees F. On
> other
> commercial maps I have had, it usually hovers around 190 degrees max under
> high
> duty cycle conditions.
>
> Hope this helps.
>
> 73, Bill W6WRT
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