-----Original Message-----
From: Kevin Nathan [mailto:[log in to unmask]]
Sent: Sunday, May 16, 2010 4:12 PM
To: [log in to unmask]
Subject: RE: amplifier use questions
Hi Gary and Lloyd,
I'm back from Europe and had a great time. I just turned mail back on here
for the group but wanted to weigh in on this one.
Gary, Lloyd is right. The absolute necessity you will have to have is some
sort of tuning device such as the TW-1 or other tuning aid that will
indicate maximum RF output. John Miller is also right in that once you have
tuned your amp a few times, you will be able to tune it quickly on different
bands. Of course, if you could swing the money, the very easiest is a no
tune solid state amp but tubes are OK too. If you are looking for a new
amp, the most reasonably priced and most bullet proof amp would be the MFJ
Al-80B followed closely by their AL-811H. For this last, replacing the
811A's with 572B's is a great move and makes it almost bullet proof as well.
If you are looking used tube amps, the Heath Kit SB-1000 is good as well as
their SB-200 and SB-220 if you don't want 160 meters. Of course, there are
Alpha's and other amps out there but the prices start climbing quickly and
you can end up paying as much for a used Alpha as a brand new solid state.
Good luck and very 73.
Kevin :)
Amateur Radio: K7RX
-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Lloyd Rasmussen
Sent: Sunday, May 16, 2010 11:48
To: [log in to unmask]
Subject: Re: amplifier use questions
Obviously, if you want to switch bands quickly during a contest, an amp with
plate tuning and loading controls and a bandswitch will slow you down a
little. But it doesn't prevent me from doing fairly well in contests.
I use a 39-year-old Yaesu FL2500 amplifier (which uses five 6KD6 horizontal
output tubes in parallel and struggles to get much more than 500 watts PEP
output. A rather low-impedance, low-voltage, somewhat inefficient circuit.
The manual recommends no more than five seconds of continuous carrier at the
SSB full-power setting. Failure to observe this precaution may result in
destination of the tubes! (A bad Japanese translation).
I used to tune this up with a Conway gimick, and now tune it up with the LDG
TW-1 wattmeter on the tone setting. I tune for "maximum smoke" (max RF
output). I have to make my FT950 tune up into the linear amplifier's input
circuit, since the impedance is somewhat lower than 50 ohms. It requires
about 50 watts of driving power.
If you get an amp with a real output tube or tubes, such as the 3-500Z or a
set of 811A's, the amp will be more rugged than mine.
Last Sunday you heard this setup on the 20-meter net.
If you have any other questions, please let me know.
73,
Lloyd Rasmussen, W3IUU, Kensington, Maryland
Home: http://lras.home.sprynet.com
Work: http://www.loc.gov/nls
> -----Original Message-----
> From: For blind ham radio operators [mailto:[log in to unmask]]
> On Behalf Of Gary Lee
> Sent: Saturday, May 15, 2010 11:14 PM
> To: [log in to unmask]
> Subject: amplifier use questions
>
> I have never used an amplifier before, but am now considering purchasing
> one.
>
> There are some nice no tune solid state amps out there, but they are
> pricy.
> What is the general experience out there with using tube type amps and
> tuning them up?
>
> I am thinking about something in the 5 or 600 watt range.
>
> I would appreciate any information and experiences.
>
> 73
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