[SixClub] 6 meter repeater PL tones

[Chris Boone]

The ONLY incidence I know of where a XMIT PL was causing problems was on a
VHF Police rptr in Conroe, TX (North of Houston) back in the 80s and 90s...
The split on the rptr was 1.14MHz (gotta love the NO standard VHF commercial
stuff!)...AND there was a local AM station in town on (yeah you guessed it)
1140 kHz....daytimer only but a lot of times, the station was "accidently"
left on the air at night...though the main pattern (it was directional to
the east protecting WTAW 1150 in College Station....WTAW meant Watch the
Aggies Win) didn't point at the rptr tower--the AM was NNE of the rptr
site--and at night more than the daytime, and NO ONE ever figured out WHY,
the mix of the AM carrier would cause the rptr to lock up on the air...soooo
the city technical guy made the xmtr Carrier out....no more problems but the
mobiles heard other systems when the band was open (Which happens a lot
along the Gulf Coast!); he got with me about the problem (as I was working
for the local power company,  GSU in the telecom dept and personally knew
the FCC Engineer in Charge at the Houston Field office from high school) and
one night I had a service tech go over to the AM site and open the
transformer fuse!!! The station got the hint the next day when they had NO
power in the building and the FCC just HAPPENED to show up that
morning....OOPS!!!! :)

If you have a mix on an amateur repeater that causes that problem, using PL
will just cover it up; it WONT go away unless YOU FIX it externally..AND 6m
rptrs in areas were FMs are spaced 1MHz apart OR a local AM on 1000kHz, it
can happen....which is why the 1.7MHz split from NW US makes sense...no
problems with FMs and there are FEW 1700 AMs.....(Ive seen this happen on
220 with the 1.6MHz offset (with FMs spaced 1.6MHz apart) and even 440 rptrs
where a trunking system may be on site and TWO xmtrs are  5MHz apart...I had
a problem with a 2m rptr back in the early 80s where two RCC/Mobile phone
channels 600kHz apart on the SAME tower locked up my rptr which was 3 miles
away airmiles...took the GasFet off the rptr and the issue went away)

Chris
WB5ITT

> -----Original Message-----
> From: sixclub-bounces at mailman.qth.net [mailto:sixclub-
> bounces at mailman.qth.net] On Behalf Of Richard J. Fiero II W5TFW
> Sent: Wednesday, April 21, 2010 4:14 PM
> To: World Wide Six Meter Club
> Subject: [SixClub] 6 meter repeater PL tones
> 
> OK,
> 
>  I'll go there I was  trying to stay OUT of this,.... but here is the
> arguement I was given,
> 
>  it seems there are some that believe that the PL tone,.. ( on 6
> meters )....
> if they are both the same for ENCODE & DECODE,...... tend to PING / pong
> each other !
> 
>   I do NOT know this to be the case,....... but thats the way it was
> explained to me..........
> 
>  I am FAR from an expert, ( more like a  gossip than a  TECH,. ) but thats
> the way I have heard it,   I dont run a pl on both sides, on mine,.....
and
> have never tried it at all.
>  So I do not know this to be the case at all.
> 
> 
>                                   Joey
>