[TenTec] Hercules 444 amp

[Mike Hyder -N4NT-]

I owned the last 444 Ten-Tec worked on.  It had taken off and burned a
couple of the circuit boards.  They fixed it and added more negative
feedback.

I sold it, telling the buyer that Ten-Tec wouldn't work on it.

I wouldn't suggest you even consider getting one of those amps unless you
want to replace all the RF section with new.

Another thing you might want to consider is this:  The 444 has a fan that
sounds like a 707 until the heat sink temperature reaches a high enough
temperature to switch the fan to high speed -- then it sounds like a 747.

73, Mike
N4NT@chartertn.net

----- Original Message -----
From: "dslosty" <dslosty@pipeline.com>
To: <tentec@contesting.com>
Sent: Saturday, July 21, 2001 9:39 PM
Subject: [TenTec] Hercules 444 amp


>
>
> I've been looking for a decent Hercules 444 amp to go with my Omni-C for
> some time. I came across one that didn't work, and the imbalance
> shutdown light was on.
>
> The amp in question probably has one or more blown finals.
> Ten-Tec used MRF428's in the final. Their service dept tells me
> that original spec MRF428's are no longer available. They also
> mentioned that replacement MRF428's made in the last few years
> have higher gain (HFE) than the originals and will "take off"
> and blow in a few moments if used. Apparently, no other subs are
> suitable. Thus they consider the amp unrepairable.
>
> Has anyone had experience with this?
> I'd think that with a lot of trial and error, for someone with time
> to "burn", negative feedback could be added to reduce final gain.
> The problem would still be to balance both modules. The imbalance
> protection circuit would immediately shutdown the amp if that wasn't
> done. Obviously, Ten-Tec would not want to do this sort of
> reengineering.
>
> One of these days, I'd still like to get a 444.
> Are there any owners out there who have gone through this?
>
> 73,
>
> Doug/WA1TUT



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