Re: [TenTec] Hercules II problem

["Donald Watters" <dwatters@ns.sympatico.ca>]

John -

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" <jac.trademarks@tiscali.co.uk>
To: "Donald Watters" <dwatters@ns.sympatico.ca>
Cc: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
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 
> as
> load. Right now the dummy load is not cabled to the main antenna switch, 
> but
> I can soon re-connect it. I can also bypass the ATU, although that seems 
> to
> make no difference.
> Tricky ....................... but I still think it is most likely inside 
> the
> Herc circuitry.  Unless someone knows better, or you are right and there 
> is
> 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 
> > actual
> > 50
> > Ohms?  If the Z is low then excessive current will be drawn and the PS 
> > will
> > shut
> > down.
> >
> > Just a point and a possibility, OC.
> >
> > Don,  VE1BN
> >
> > ----- Original Message -----
> > From: "JohnCrux" <jac.trademarks@tiscali.co.uk>
> > To: <tentec@contesting.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
> > > 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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> > > TenTec@contesting.com
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