I have to agree that the Hercules II is an excellent amplifier. I
have been using one for several years now and its just like having a
500w (output) tranceiver when its hooked to my Omni-V. I can get
over 500w into a dummy load on 80m with 25-30w of drive.
The only really serious problem I had (so far !) was a final
transistor failure which a visit to Sevierville fixed for me. It took
the TT man about 45 seconds to open the box and diagnose which one
had blown ....
I do have a strange intermittent problem with it right now. The
output vacuum relay will suddenly stop working, usually, but not
always, when the amplifier has been on for a while. Static testing on
the XYL's dining table has failed to reproduce this fault, but makes
me unpopular. (The shack under the stairs is much too small for bench
work). I have swapped the diode across the relay coil. The relay
driver transistor seems perfectly OK. It does not get hot.
There is no warning; the SWR suddenly rockets upwards and the RF
output goes nowhere - well, its stuck in the box someplace ! I have
to immediately disable the amplifier and go barefoot for a while.
Sometimes the relay starts working again after leaving the amplifier
switched off for a while. But sometimes it does not ... Then after a
night switched off, it works fine, for a bit or even for hours. Then
bang; no RF output again and a horrific SWR.
For example, it quit tonight, so I left the amplifier on for several
hours before trying again. It worked !!! I used it to work E44DX on
80 CW/SSB. I then made a very serious attempt to cause the thing to
fail. I pounded away at 25-30 wpm into a dummy load for long enough
to get the internal fan to run at its full speed. I let it cool
down and tried again. The relay behaved perfectly. The amplifier
actually runs pretty cool at 500w on CW, so internal heating should
not be the cause. All the relevant devices are in the cool air flow
going into the Herc II.
I guess that either I have a weird relay control board problem, or I
have a sticking vacuum relay problem. The relay is expensive. I wonder
if anyone out there has had a similar problem and if there is a fix
for it that does not involve buying a $100 relay .... ??
Yes, I already asked TT service; they do not seem to have run into
this oddball problem before. The best idea I have is to temporarily
route some (thin) coax to the relay coil and monitor the actual
relay keying voltage with a meter or LED. If the relay quits and the
keying volts are still reaching it, then its got to be the relay. If
the keying volts vanish, then its the control board/relay driver.
Does that sound about right, or am I missing something obvious ??
On 19-Feb-99 Jack Van Demark wrote:
> A local ham here in Houston has a TenTec Hercules II for sale. He
> is not
> on the Internet so no e'mail. His call is N5ECP, Jeff Salmons and
> phone number is 281-855-3632.
> The unit is in excellent physical and working condition and he is
> $850 shipped.
> If looking for one of these excellent but rare amplifiers you might
> Jeff a call.
> Jack WN5A
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