I bought my AL-1200 years ago from Radio-Kit, when they had a store-front
in some Mall or Industrial Park in NH. I also invested in tube futures by buying
a spare final (only $225 then). I still run the original tube and it still puts
out
the rated power.
I run it on RTTY, but have never had the guts to crank it up to 1,500 out. I
usually run it at 1,000 out. I do run it at 1,500 on CW & SSB though.
They say it is built like a Battleship and I can concur with that. On a couple
of
occassions I forgot to turn the power down on the FT-2000D, but did notice
the Kenwood SW-2000 bouncing off the peg. I corrected that immediately.
Didn't seem to bother the amp though, no creaks, groans or arcs.
I can't think of any reason I should buy one of those $4-5K Amps, what do they
do that the AL-1200 won't !!
73, Dick, W1KSZ
> From: dezrat1242@yahoo.com
> To: amps@contesting.com
> Date: Thu, 2 Jul 2009 10:46:17 -0700
> 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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