[TenTec] Dead Omni VI Rcvr Update

[John - G3JAG]

One thing that occurs to me is that the front end tuned circuits/filters
are not necessarily pin diode switched ... in my Omni-V reed relays are
used, two for each band. I had to replace a pair of relays, because one
was jammed shut. The symptoms were weird in that the rig was OK on some
bands, but not on others ... In other words the jammed relay affected
more than just one band. Now if you have a relay problem or a relay
driver problem you may have several or even no filters in circuit and as
a result the radio will certainly be deaf. 

Incidentally, at first I went down the pin diode route. I changed all
the diodes, but only the relay change gave a positive result. I now have
a heap of perfectly good spare diodes in a box. 

OK, my radio is an Omni V, but I suspect the front end is not that
different. If it is then shred this msg !!

73 John G3JAG

On 06-Sep-99 Hal Offutt wrote:
> 
> Hello Again,
> 
> Thanks to everyone who sent suggestions about my dead Omni VI
> receiver.  I
> got six replys and they all contained some good suggestions.  I have
> spent
> some more time with the rig and have some new data but no solution so
> far.
> I can hear the 15 Mhz oscillator in my other rig so it seems to be
> working.
> And I can hear my other rig (on low power) on all bands in the Omni,
> but
> just barely, so the receiver is actually working, just not very well.
> (On
> some bands it needs an antenna to hear the other rig and on other
> bands it
> does not.)  I also went in and visually inspected the two boards
> burried in
> the middle of the rig, but nothing seems amiss.
> 
> To answer questions that a couple of you have posed, the receiver
> does not
> work in any mode.  I have tried connecting an antenna to the aux ant
> input
> but there is no change.
> 
> Someone said that he had a similar problem six months ago and that
> the cause
> was bad pin diodes in the TR circuit.  This got me to thinking.  When
> this
> problem first happened back in January, I was operating the North
> American
> QSO Party and I think I was using two rigs.  I am wondering if I
> might have
> accidently transmitted on my Omni receive frequency with the other
> rig,
> thereby knocking out the receiver.  I know that my Yaesu FT-757 has a
> protective bulb just behind the antenna input to protect the receiver
> against idiots who do things like this.  Does the Omni have such
> protection?
> I guess I need to look at the schematic.
> 
> If this new data does not suggest an obvious solution to my problem
> to one
> of you technically-minded Omni experts out there, I guess I'll be on
> the
> phone to Omni tomorrow.
> 
> 73 and thanks again for the suggestions.
> 
> Hal Offutt W1NN
> 
> 
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----------------------------------
E-Mail: John - G3JAG <patents@dx0man.prestel.co.uk>
Date: 06-Sep-99
Time: 18:48:07

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