For interest, have you checked the SWR into a dummy load with
a thruline model 43 powermeter or other reliable wattmeter? I
have found this meter excellent and often tells me things that the
rig's meter and others do not. Again, just a thought.
161 - Don
----- Original Message -----
From: "JohnCrux" <firstname.lastname@example.org>
To: "Donald Watters" <email@example.com>
Cc: "Discussion of Ten-Tec Equipment" <firstname.lastname@example.org>
Sent: Thursday, July 27, 2006 7:10 PM
Subject: Re: [TenTec] Hercules II problem
> Interesting thought, but there is no indication of any impedance change
> external to the amplifier. Other bands via the same ATU are normal.
> The ATU matches both 10 and 12 to 1:1 and the Omni-V will happily run flat
> out. Turn on the Herc and its anybody's guess what will happen.
> I had exactly the same symptoms when I used my 50 ohm oil filled Cantenna
> load. Right now the dummy load is not cabled to the main antenna switch,
> I can soon re-connect it. I can also bypass the ATU, although that seems
> make no difference.
> Tricky ....................... but I still think it is most likely inside
> Herc circuitry. Unless someone knows better, or you are right and there
> something amazing going on. Note that the actual antenna used seems
> irrelevant and the SWR shown on the ATU and on the external bridge appear
> very stable.
> 73 John G3JAG
> On Thursday 27 July 2006 21:24, Donald Watters wrote:
>> John -
>> Are you absolutely positive that the load inpedance on 10/12M is an
>> Ohms? If the Z is low then excessive current will be drawn and the PS
>> Just a point and a possibility, OC.
>> Don, VE1BN
>> ----- Original Message -----
>> From: "JohnCrux" <email@example.com>
>> To: <firstname.lastname@example.org>
>> 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
>> > under
>> > 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
>> > commercial
>> > ground bus wire connections linking everything are rock solid as are
>> > the
>> > coax
>> > connections.
>> > For a few days there was no problem getting 500 watts from the Hercules
>> > II on
>> > 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
>> > haunt
>> > me. The Herc trips out ("fault") at around 150 watts out on 10m and at
>> > around
>> > 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
>> > also
>> > 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
>> > 12m.
>> > OK; I already swapped the 10/12m low pass filter in the Herc. The
>> > Omni-V
>> > is
>> > 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",
>> > but
>> > 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
>> > switching
>> > 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
>> > unused
>> > circuits.
>> > 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
>> > the
>> > contacts ..... Surely someone has seen this ????
>> > Yes, I know it is no longer made, but the Herc is a super amplifier and
>> > I
>> > have
>> > made many QSOs with it. Just need to get 10/12m back in service
>> > reliably. 73 John G3JAG
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