I will certainly detail my experience. Hopefully, I will not repeat the
failure. I am replacing the Plate RF coke with the current one for the
AL-80B.
Doug
----- Original Message -----
From: John / NS1Z <ns1z@arrl.net>
To: Doug Person <w4dxv@ibm.net>
Sent: Friday, June 11, 1999 1:00 PM
Subject: Re: [AMPS] Finally - a real amp
> If you don't mind, I would appreciate hearing from you on your results
with
> the tube. I have one that needs to be replaced and, being cheap, I would
> like to get one inexpensively. 73
>
>
> At 11:02 AM 11-06-99 -0400, you wrote:
> >
> >Well, I opened up the AL-80A to see what had happened. I was stunned. I
> >expected to find a fried plate RF choke as Vic suggested. Instead, when I
> >removed the 3-500z, I first noticed the top inside surface of the glass
had
> >a powdery substance on it in pattern not unlike the fins. Then I
discovery
> >the really interesting new characteristic of the tube. There was a hole
> >clear through the glass as though it had been shot by a high-powered
laser.
> >There are fine cracks around the hole and the glass had actually flowed
> >inward almost half an inch. Wow. Watch out for 17 meters on this baby.
I
> >guess I'll replace the choke before I put the new tube in. I tried to
order
> >a Taylor 3-500zg from RF Parts. They were back-ordered, so I accepted
their
> >RFP Special which I suppose is their Chinese version.
> >
> >Doug -- W4DXV
> >
> >----- Original Message -----
> >From: Vic Rosenthal <rakefet@rakefet.com>
> >To: amps <amps@contesting.com>
> >Sent: Friday, June 11, 1999 10:32 AM
> >Subject: Re: [AMPS] Finally - a real amp
> >
> >
> >>
> >> Doug Person wrote:
> >> >
> >> > That seems quite a bit less than what the manual suggests. However,
the
> >> > reduced power would hardly be noticable to anyone. I wonder what the
> >> > affects of SSB would be rather than full carrier. If I tune up the
amp
> >> > using no more than the 400ma plate current and 65 watts drive, would
> >pushing
> >> > the power to 100 watts PEP input during normal SSB operations result
in
> >> > additional stress on the 3-500z, or perhaps increase distortion?
> >>
> >> The single 3-500Z can be tuned and loaded to 550ma single tone (CW) for
a
> >very
> >> short period in order to establish the correct operating conditions for
> >the peak
> >> of the SSB signal. It should then be driven by no more than about 65w
PEP
> >to
> >> give about 1000w PEP output. Average plate current will be much less
than
> >550
> >> MA. However, when operating CW, the amp should be loaded to 400 MA
> >maximum! I
> >> find that my SB1000 produces around 800 watts CW output with 400 MA
plate
> >> current and around 125 MA grid current.
> >>
> >> > Now that I've gotton your input, I'm sorry to report that while
tuning
> >the
> >> > AL-80A on 17 meters with 500ma ip and 150 ma of ig, A somewhat loud
and
> >most
> >> > unpleasant noise ocurred within the amp after which there was no
current
> >> > indicated for either ig or ip. Did I fry the tube?
> >>
> >> You probably fried the plate RF choke which has a resonance near 17
> >meters. You
> >> can order a replacement from Ameritron for about $25. The one made for
> >the
> >> AL80B works properly on the WARC bands. I have had one of these in my
> >SB-1000
> >> (which by the way is *very* similar to the AL80) for some time and it
> >works
> >> quite well on all bands, including WARC.
> >>
> >> 73,
> >> Vic, K2VCO
> >> Fresno CA
> >>
> >> --
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> >> Submissions: amps@contesting.com
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> >>
> >>
> >
> >
> >--
> >FAQ on WWW: http://www.contesting.com/ampfaq.html
> >Submissions: amps@contesting.com
> >Administrative requests: amps-REQUEST@contesting.com
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> >Search: http://www.contesting.com/km9p/search.htm
> >
> >
>
>
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