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[Amps] Ten Tec Herc 444 (original Herc)

To: "amps@contesting.com" <amps@contesting.com>
Subject: [Amps] Ten Tec Herc 444 (original Herc)
From: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 19 Jan 2006 16:07:01 -0600
List-post: <mailto:amps@contesting.com>
On Thu, 19 Jan 2006 12:05:07 -0800 (PST), Dave Haupt wrote:

>The original Hercules I (model 444,
>ran on 50V, not 12), is no longer supported, due to RF
>transistor obsolescence.  I have one on the bench
>right now, fortunately the RF devices are fine, and
>it's a power supply problem.

I've got one too. When I bought it (used), it was wired for 
120V. I rewired it for 240v, and it didn't work -- blew fuses, 
as I recall. What I found was that one of the Molexes was wired 
wrong -- probably built on a Monday morning. Corrected that and 
it ran fine -- except that:

As it warms up, the voltage to which the power supply regulates 
drifts up and causes the protection circuit to engage, which 
prevents it from transmitting. TenTec told me this was a known 
problem, but that since they had to discontinue the amp (thanks 
to Motorola discontinuing the output devices), they had not put 
in the engineering time to fix the drift problem. 

Mine is in good shape, but I need to fix the regulator drift 
problem. If anyone knows how, I'd love to hear about it so that 
I don't have to reinvent the wheel.

Jim K9YC


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