[TenTec] Omni VI and power supply occilation???

[denton]

Here are some other things I just remembered...
When the Omni quit on me the first time, at TT's suggestion I did some 
signal tracing...
Using the 'scope, I had signal ampflication until the driver transistors...I 
replaced them and had signal amp to the output of the drivers.
Local commercial electronics outfit said the finals would cost me about 200 
bucks or a bit less and they would not be a matched set.
TT said they would replace the finals with a matched set and realing the 
unit for that much bucks.
When I ran my diagnostics, I also noticed that the finals were not the mrf 
458's that is indicated on the schematic, but were a pair of SC something or 
other. From my observation it seems to me that the finals had been replaced 
before I got the rig.

----- Original Message ----- 
From: "J. Reed" <jhreed at chilitech.net>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Tuesday, April 19, 2005 8:51 AM
Subject: Re: [TenTec] Omni VI and power supply occilation???


> Good morning once more Denton,  my inquiring mind
> is starting to focus on your 'supply' which is starting
> to sound like a non-filtered charger, hitting the
> batteries at 35+ amps on positive peaks of about 20+ volts
> every 120th of a second.  The Omni can't take that
> (in my opinion) too long.  Also, at the initial start
> in the morning, it's posssible that there's a light
> coating of hydrogen bubbles on the plates of the
> batteries and for a fraction of a moment, the spikes
> go straight to the Omni.  To test this idea, put your
> scope on the batteries (without the OMNI connected),
> and check for pulses... IF you don't have a scope,
> take your AC voltmeter and set it for about 20 vac
> and see just what the indicated AC reading is.
> Remember, the 1.414 x AC value will give you the peak
> value that might be causing you grief...  just some thoughts,
>  ----- Original Message ----- 
>  From: denton
>  To: Discussion of Ten-Tec Equipment
>  Sent: Saturday, April 09, 2005 11:14
>  Subject: [TenTec] Omni VI and power supply occilation???
>
>
>  I recently purchased a used Omni VI that quit transmitting, sent it in to 
> TT
>  for repair and alingment. TT replaced the finals and some other work...
>  I recieved the repaired Omni yesterday and wasted no time getting back on
>  the air.
>  This morning....no rf out AGAIN!!! Exact same sympthons as before.
>  I made a call to the TT repair department, and they said since I run a
>  homebrew power supply, I may have an ocillation from the power supply 
> that
>  is destroying the finals in the Omni.
>  What ocillation??
>  I have used this power supply for years. It is currently feeding an FT 
> 990
>  and uhf/vhf radio without problems. The power supply has fed various TT 
> hf
>  rigs thru the years without problem. Is there something unique about an 
> Omni
>  that will not allow it to be used in my station on the existing power
>  supply??
>  The power supply is currently hooked up to a pair of absorption mat deep
>  cycle batteries with a blocking diode between the B+ and the batteries. 
> It
>  has been used this way for quite some time without problem, and the power
>  supply alone is capable of 35 amps continous all day long.
>  TT also tried to tell me this morning that I may have to run the Omni, 
> when
>  it gets back from being repaired a second time, on a separate power 
> supply
>  that will shut down when it detects ocillation.
>  Anyone run across this before...thanks....
>
>
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