Fred,
If you don't know, there is a specialized Amplifiers reflector and
no need to use the DX reflector for amp stuff.
Anyway, as an owner of two Commander HF-2500 amps I can tell
you that it's a good piece of equipment.
High points:
* very strong and rugged mechanical construction - still at a
desktop size .
* conservative ratings RF components ( eg. huge bandswitch ).
* small and totally quiet hypersil XFMR.
* very good air cooling ( in excess )
* quiet and smooth QSK operation ( if you want this option )
* grid trip protection ( protects the expensive tubes from accidental
overdrive ) + 3 minutes timer protection during the filament warming.
* uses american-made Eimac 3CX800A7 quality tubes
* excellent spectral purity ( IMD and harmonics ), actually little bit
better than AlphaPower 87A or Titan 425 amplifiers using same
tubes. It uses a heavy duty Pi-L output filter
* very smooth 1:6 vernier drive variable capacitors make the tuning
very easy and pleasant.
* output power in exccess of 1.5kW key down output with abt 65-70W
of drive. Mine were able to put 2250w on dummy load and remain
cool.
* easy to maintain and repair.
* excellent customer service. Pat Stein is doing a great job.
Low points:
* no SWR/PWR meter ( only grid and plate current and HV monitoring)
I beleive that most hams have an independent SWR/PWR meter in their
shack but for an amplifier in this price class I beleive it should
have one.
* voltage doubler HV rectifier it's theoretically less good than full
wave
rectifying. Anyway, the HV drops only 5% when fully loaded and the
electrolithic HV capacitor are of very good quality and the filtering
it's
very good.
* dis-assembling and assembling the HF-2500 amp it's quite laborious.
* the manual it's OK but lacks some explanations and the diagrams
have some mistakes.
* some early models had a soldering problem on one of the HV diodes
but it's easy to repair.
If you're going to check the market for this class of amplifiers and you
will analyze the competitor amps by ruggedness, power output, component
ratings, overall reliability, circuit design, spectral purity, cooling,
ease of
use........, you'll find that Commander HF-2500 it's the best choice.
The competitors in this class are: Ten-Tec Titan 425 and Ameritron
AL-800H ( with Eimac tubes ) ; AlphaPower 91B and QRO HF-2500 .
( with russian tubes ).
Please let me know if you need more infos.
73 de Morel, 4X1AD
> ----------
> From:
> fcarvalho@integral.com.br[SMTP:fcarvalho@integral.com.br]
> Sent: þéåí ùéùé 24 àôøéì 1998þ 16:01
> To: DX@ve7tcp.ampr.org
> Subject: Commander 2500 HF amplifier
>
> Commander users would tell us the high and low points of the 2500 HF
> amplifier ?
>
> thanks
>
> Fred
> e-mail : py2xb@integral.com.br
>
>
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