Are you absolutely positive that the load inpedance on 10/12M is an actual
Ohms? If the Z is low then excessive current will be drawn and the PS will
Just a point and a possibility, OC.
----- Original Message -----
From: "JohnCrux" <email@example.com>
Sent: Thursday, July 27, 2006 5:14 PM
Subject: [TenTec] Hercules II problem
> Desperation time.
> I repaired my 9420 PSU and reset the four 25 amp rails at exactly14 v
> load. I repaired and re-aligned the Omni-V.
> Then I re-assembled the entire station, including the auto-atu. All
> inter-connecting/control cables are original TT. My added 120 amp
> ground bus wire connections linking everything are rock solid as are the
> For a few days there was no problem getting 500 watts from the Hercules II
> any band 10-80m (not tested 160; no antenna at present.)
> That held good for a week or so. Then a very old problem came back to
> me. The Herc trips out ("fault") at around 150 watts out on 10m and at
> 250 watts out on 12m. Switch off and back on, and all other bands work as
> before. The SWR remains as before on all meters ( Herc, ATU and external
> SWR/power bridge. It is 1:1 or very close.
> But it does not always trip. Today after having it trip at 150 watts on
> 10m, a
> little while later it ran perfectly OK on 12m at 400 watts out. I have
> had 10m return to normal output from time to time.
> It is unpredictable, except that if it trips on 10 then will probably do
> so on
> OK; I already swapped the 10/12m low pass filter in the Herc. The Omni-V
> working fine on all bands including 10/12m and gives normal output.
> My best guess is that this is maybe a mechanical problem with one or more
> bandswitch relays. The front panel bandswitch is normally set to "auto",
> even if I manually select 10/12m, it makes no difference, so the switch is
> probably OK.
> The Herc manual indicates that it is not just a matter of the relays
> in that LPF for 10/12m. Other relay contacts appear to be used to disable
> (short ?) other band filters, perhaps to avoid stray resonances in the
> Anyone seen this problem (including my friends at TT service, please !)
> and is
> there a solution ? If only I could pop the covers off the relays to check
> contacts ..... Surely someone has seen this ????
> Yes, I know it is no longer made, but the Herc is a super amplifier and I
> made many QSOs with it. Just need to get 10/12m back in service reliably.
> 73 John G3JAG
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