[TenTec] Omni-A Low Power Out Problem

[Steve]

I thought I had no ALC but after investigating to make sure that the LED was
ok I find that someone had taken the front panel off and added several lamps
and has hacked up the little board on the back of the front panel.  They
tried adding several lamps to brighten up the dial..There are 3 wires going
to it from the little plug on the chassis and two of the wires have broken
off from there attachment to the front panel board. So not sure what goes
where at the moment, but think it is fixable..So at least this is the
problem with the ALC LED never going on.  They really hacked this up bad and
I don't find a schematic in the manual on this little board, so will have to
do some tracing of the circuit.

So I looked at the ALC line directly. reseated the SWR/TR board  and now
there is some ALC action. I have also checked that the ALC set pot on the
LLD board is functioning and it does. But still the power out is lower than
what I think it should be. I have also doubled checked my power out and find
that I can get over 100 watts out on 3.5 and 7.0 sometimes get power out on
160 but never get more than 65 watts on the high bands. The 160 problem is
trouble some.

So some progress is being made.  Think I will get this front panel problem
solved first and put back on the radio before going further with the power
output problem.  It looks like someone might have changed the red LEDs but
can not be sure.  There are 220 ohm resistors in the anode and cathode leads
of the OT lamp and a 330 ohm resistor in one of the legs of the ALC lamp.
The schematic I have does not show either one of these.  The board part
number is 90456.  I think I know where the 3 wires from the chasses mount to
the board but like I said before I don't have a layout of that board in my
manual.  I will work on getting this thing back to stock and then get after
the Power out problem.

Whoever owned this also made several other mods that need to be removed.
They added a backpanel switch that takes the relay which grounds the
receiver input to ground on Tx in or out of the circuit.  So when the witch
is thrown in one direction the relay is functional and in the other it
doesn't work.  Not sure why you would want to do that.  But I am going to
remove it.  They also added a connector on the back for speaker out and
added a connector inside the case for the speakers in the bottom so that
when you take the bottom off you do not have unsolder the speaker wires.  I
will leave those two mods in.

Steve
.
----- Original Message -----
From: "Al Scanandoah" <k2zn@rochester.rr.com>
To: "Steve" <sswhite@mchsi.com>
Sent: Sunday, August 18, 2002 11:30 AM
Subject: Re: [TenTec] Omni-A Low Power Out Problem


> Steve
>
> When you get full power out on the lower bands, but no ALC activity,
> where is the DRIVE control set?
>
> It sounds like you may have a problem on the low level driver board.
>
> Al, K2ZN
>
> Steve wrote:
> >
> > Hi All
> >
> > I have a very nice Omni-A that has low power ( 75 Watts) out on the
higher
> > bands ( 20 Meters and up) but puts out full power on lower bands and
there
> > is no ALC light action ever.  Now I know that some of you must have seen
> > this before.
> >
> > Do I have a pair of finals starting to go?  Or is there some other
circuitry
> > that is going bad on this radio?
> >
> > Any help or thoughts or anecdotal solutions will be helpful.
> >
> > steve
> >
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