[W3GV] Erie CG conducting drills, but 146.61 on CG Ch 16 REMAINS

[Craig Hill]

Hi Rich,

   I'll attempt to tell you what is happening.  In electronics there is a
process called mixing.  Almost all receivers are of the superheterodyne
design.  In a superheterodyne receiver, the incoming signal is selected and
it is mixed with a local oscillator carrier.  The mixing results in the sum,
difference, and two original signals at the output of the mixer stage.
These are fed to the IF (intermediate frequency) amplifiers, then to the
detector, and then to the audio amplifiers.  However, the harmonics
(integral multipliers) of the transmitted signal will mix with the local
oscillator and also harmonics of the local oscillator and also produce sum,
difference, and original signals.  Since you are close to 61 the harmonics
would be strong enough to get through the first stage of your receiver.  The
repeater's harmonics are attenuated to meet FCC requirements.  Therefore the
problem is on your end.  What can you do about this problem.
1.  A better receiver to hear the marine frequencies may have better
selectivity and get rid of the problem.
2.  You can add filtering to the input of your marine receiver and it may
eliminate the problem.
3.  You can move your receive antenna and maybe eliminate the problem.
4.  Shielding your receiver may help.

But the problem is NOT the fault of the repeater.  What you are hearing is
an image frequency.  Do some study on image frequencies in the Radio
Amateur's Handbook and other sources and you may find a solution.  Many
people have dealt with these problems and have completely solved them.
----- Original Message ----- 
From: "Richard Wagner" <n3bwg at yahoo.com>
To: "RAE LIST" <w3gv at mailman.qth.net>
Sent: Thursday, April 21, 2011 10:24 AM
Subject: [W3GV] Erie CG conducting drills, but 146.61 on CG Ch 16 REMAINS


> There still has not been a single individual to come forward and why it is
vital that 146.61 continue to impose itself on top of Erie CG primary
distress/calling channel 16 !!
>
> No one has reported what is possibly mixing with 146.61 output frequency
to jam a vital service as US Coast Guard every single day lately!
>
> Complaints to FCC are very likely from anyone experiencing the same
problem from with close range of 146.61 repeater.
>
> 11:18AM USGC was supposed to be conducting drills, but it is entirely
jammed whenever anyone is yacking away on 146.61.
>
> //Rich//
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