On 8/21/2010 9:35 AM, Art Trampler wrote:
Jerry,
I'm not familiar with switch on back of rig for AUX RX...only on front of
rig next to AGC.
That's where it is on the Omni VI I see when I checked the manual. On my
Corsair II its on the back panel and handles RF. Tends to go open
disconnecting the receiver from the transmit antenna. So its diode
switched in the Omni VI.
Am I missing something?
Funny how many (different) answers one question got!
There are thousands of parts and connections between the antenna and the
speaker, and any one or a group of them can have been badly soldered or
leads welded to chips inside diode, transistor, or IC packages. And for
all those that answered, some have experienced one or more of those
failures. Could be signal cables, or card edge connectors. You can
isolate by signal tracing or signal injecting to find where the signal
is lost. Or you can shotgun cleaning every cable and board edge
connector with a drop of DeoxIT and some exercise. That includes the
insulation displacement cable connections. Maybe you can induce the
failure and recovery by applying heat (hair dryer, hot air gun) and cold
(Freeze Mist was made for that job) alternatively, at first generally,
then do a binary chop (each time do half the area previously temperature
cycled) until you get it down to the part. Sometimes another shotgun
technique is to resolder a suspect board and some in other Tentecs have
been known to need that, but that's only really successful if your
soldering is better than the factory's.
Sometimes its shock or vibration that brings on the fault, but most
often its heat if it recovers after the radio has been off a while. You
can speed those up with hot air and Freeze Mist.
Art
-----Original Message-----
From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
On Behalf Of Dr. Gerald N. Johnson
Sent: Thursday, August 19, 2010 10:21 PM
To: tentec@contesting.com
Subject: Re: [TenTec] Intermitten Omni VI RX Falloff
Aux RX switch on the back of the radio. Needs cleaning.
73, Jerry, K0CQ
On 8/19/2010 10:15 PM, Art Trampler wrote:
Hey All,
On my Omni VI Opt 3, the RX periodically drops off 20 to 25db, using a
6db/S-unit scale. If I wiggle the RF gain it can pop back, or if I go key
down for one “dih.” I haven’t tried simply closing the PTT to restore (as
opposed to any transmission) but I think that would also do it.
Wiggling the RF gain makes me suspicious of that control or the board
its attached to. Likely there's a great voltage change on that part when
going to transmit and returning to receive to break down the errant poor
connection. Could be IN the pot, or its connections, or somewhere on the
board its mounted on.
I’d think “Relay” or “Diodes” if it only popped back with closing the
PTT/sending; I’d think bad solder joint if it was only the RF gain.
What’s
interesting is that the RX is not lost, just significantly
reduced/attenuated.
Your thoughts?
Thanks,
Art
Art Trampler, KØRO
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