[TenTec] Omni VI and non TT Amp

[Rick, NJ0IP / DJ0IP]

Chas,

I am not familiar with the internal layout of the AL 811A amp.  When running
a continuous duty cycle mode, I would be sure that the power supply's
electrolytic capacitors get enough cooling (i.e., probably use an additional
fan).  You might want to check how hot they get (before the contest begins),
by feeling them with you hand after a long transmission or two, but BE SURE
TO TAKE CARE when dealing with an open chassis and high voltage!

73
Rick

-----Original Message-----
From: tentec-bounces at contesting.com [mailto:tentec-bounces at contesting.com]
On Behalf Of Charles Greene
Sent: Thursday, November 08, 2007 4:42 PM
To: Rick Denney; Discussion of Ten-Tec Equipment; Discussion of Ten-Tec
Equipment
Subject: Re: [TenTec] Omni VI and non TT Amp

Rick and All,

I have a Ameritron AL0811A with three 572B tubes.  The power output 
is about the same with the 572Bs as with the 811As on SSB or CW 
because the power output is limited by the power supply voltage and 
current.  However, the 572Bs have much more plate dissipation than 
the 811As, so I can safely run 400 or 500 watts output using PSK31 or 
RTTY, a practice that would overheat and warp the plates of the 
811As.  When I acquired the Al-811A amp, it needed new tubes anyway, 
so I just bought 572Bs, and did not change the amp in any way.

Chas W1CG


At 12:06 AM 11/7/2007, Rick Denney wrote:
>Ken Brown writes...
>
> > Last time I had an amplifier using anything like 811A tubes, they
> > were actually 572B, and it took two of them to get 650 to 800 watts
> > out. It was a Heath SB-200. Is that really an 811A?
>
>I was talking about the Ameritron AL-811a amplifier, which uses three
>811a transmitting tubes, not the tube itself. The 572b tubes are
>indeed capable of greater output because of their higher plate
>dissipation rating, their greater grid current rating, and their
>higher plate voltage. Yes, the 572b is "like" an 811a tube, and some
>use them in amps designed for 811a tubes because of their perceived
>greater durability, but they aren't really the same.
>
>Rick, KR9D
>
>---
>Richard W. Denney, Jr. PE|Iteris, Inc.
>Associate Vice President |107 Carpenter Dr. Ste 230 |    703.925.3819
>rwd at iteris.com           |Sterling, VA 20164        |Fax 703.471.1757
>
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