[TenTec] 566 v3.028

[Ron Castro]

That's what fixed the headphone problem initially for me, but the factory
built a little plug-in board with chokes and caps that installs inside the
radio.  That fixed it for good!

Of course, the whole shack should start with a good, clean 'star' ground and
elimination of ground loops, and if the problem persists, ferrites on each
of the suspect conductors into and out of the transceiver.

             Ron Castro
                  N6IE   
         www.N6IE.com
              Member:
         REDXA   NCCC
         NCDXF   ARRL



-----Original Message-----
From: tentec-bounces at contesting.com [mailto:tentec-bounces at contesting.com]
On Behalf Of Jim Brown
Sent: Wednesday, April 04, 2012 8:15 PM
To: tentec at contesting.com
Subject: Re: [TenTec] 566 v3.028

On 4/4/2012 6:16 PM, Ron Castro wrote:
> The biggest RFI problem I found with the Orion II was RF getting back 
> in via the headphone jack.  There is a small mod board that the 
> factory can supply if that's the source of your problem.  I would also 
> check for RF getting in at the key jack.

Hmmm -- RF getting in via headphone and speaker cables is quite common in
audio gear, and there are two common ways it happens. First is via the
feedback network, which simply requires ordinary low-pass filtering. 
Second is a Pin One Problem, whereby the connector shell goes to the circuit
board rather than the chassis. Another Pin One Problem is also a likely
cause of RFI via the key jack.  The last Ten Tec transceiver I owned, an
Omni V, was built with Pin One problems at all the RCA connectors at the
back.

The band-aid (that is, without going inside to actually FIX the Pin One
Problem) is to add a ferrite choke with enough turns through the core to put
the resonance in the frequency range where there is RFI.

73, Jim Brown K9YC
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