[RFI] Tower Intermod - Control Lines

[K1TTT]

And DON'T rule out something in the shack!  I ran up and down 3 towers here
chasing one, putting ferrites and bypass caps on rotor lines and grounding
shells of hardline connectors...  The noise was always louder up the towers
than at the base... But it was also loud at the shack entrance where all the
cables came into the house, but that was just because there were so many of
them, right??  I had been close to it a couple times when I noticed that
when I switched 10m antennas the threshold for mixing went up... I pulled
apart the whole 10m station a piece at a time and couldn't stop it
completely, so it couldn't be there, right??  No, not this time... It was
the floating diode bridges in the daiwa power/swr meter 12v power inputs.
Not just one of them, as when I disconnected the 10m one, but all 6 of them
in the shack, had to be disconnected to completely stop it.  


David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
 

> -----Original Message-----
> From: K8TB [mailto:k8tb at bosscher.org] 
> Sent: Thursday, July 22, 2010 21:37
> To: Ed Richardson; RFI at contesting.com
> Subject: Re: [RFI] Tower Intermod - Control Lines
> 
> 
> Ed,
>      How far away are you from the AM broadcast stations? If this was 
> the US, there is a Google Earth app that shows this. Keep in 
> mind that a 
> possibility is that something on your system is picking up the AM 
> stations, and creating the mix. This could be rotor lines, remote 
> antenna relays, and the proverbial metail rain downspout. 
> Don't laugh, I 
> DF'd one some 35 years ago. Just slightly tapping the sections would 
> make the, in this case, 3rd harmonic, come and go.
> 
>      tom k8tb
> 
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