Hi.

I can really see both sides of this issue. With the type of tropospheric
ducting that is common in the summer months, PL can reduce a lot of
problems, although there are some types of co-channel interference that it
does not address.  I think that Harvey missed the point, though.  In most
regions of the country, PL is used to keep users of neighboring repeaters
from keying up the wrong repeater.  It isn't really intended to "close" a
repeater or make it exclusive.  It is simply an interference reduction
technique.

For example, if a repeater in my area uses 110,.9 Hz PL, and a repeater 75
miles away uses 71.9 Hz PL, then the folks that are 60 miles away trying to
work the other repeater will not bring up our repeater because they have
the wrong PL tone for our machine.  This can also help to keep spurious
crud from other services from getting retransmitted through the repeater.

The situation where PL doesn't help is where a distant repeater comes in so
strong that it actually captures the signal from the local repeater.  I
have this situation here, where a repeater in Wethersfield, NY (about 40
miles away) gets captured by a repeater on the same frequency in Verona,
NY, which is about 110 miles away.  But, with summer enhancement, it is not
unusual on 2 meters or 70 cm for a more distant repeater to capture a local
one, and PL will not address that issue.  Short of using very directional
antennas at my location, there really is no solution to that problem.

I agree that some radio manufacturers have not paid enough attention to the
accessibility of the PL encoders in their radios.  Fortunately for me, the
Kenwood TR-751A and the Kenwood TS-790 are both extremely accessible once
the speech boards are installed.  If you think that you might like to play
with FM and SSB on 2 meters, and you get the chance to grab one of these
radios, they are worth grabbing.  They have really good receivers, too.
  Anyway, one of the unfortunate sides of being in any radio service is
that technology changes as the frequencies get more crowded, and a service
cannot continue to base policies on the oldest technology out there.  Good
grief, if we did that, we'd probably still be running 2 meter AM!

Unfortunately, I have a couple of "beater" radios that I like to use for
public service events that are not equipped with PL, which I will have to
somehow equip.  I like to have these radios because if they get banged
around, or someone dumps a cup of coffee into the radio, I am not out very
much money, and I won't be very upset if I lose one.

In part, I wonder why we have to have so many repeaters that we have them
spaced such a geographically short distance on the same channel.  I dare
say that 80% of them are dead silent 95% of the time.

There is always the option, for those who are on a pretty small budget to
retrofit an older radio with an aftermarket PL encoder like the Comspec
units, as these units are generally fairly inexpensive, but not very
flexible.  I retrofitted an Icom IC-4AT that way, but can only work the 70
cm repeaters that use a 110.9 Hz PL (which is most of the machines in my
immediate area, fortunately).

I guess to sum it up, I see some advantages to PL in reducing annoying
repeater key-ups from distant signals, but I see some real drawbacks for
those with older equipment, and I think that there is some real problems
for travelers, especially for those who have an older PL encoder that is
DIP switch programmable, like the encoder in my Kenwood TW4000A.  These
things are never simple.  Perhaps, some thought should be given to
maintaining one emergency system that is either carrier operated, or uses
an agreed upon PL across the nation, assuming we can agree on anything
across the nation.  It would be dreadful to need emergency assistance on
the road sometime, and waste time trying to figure out what PL to use.  I
think this issue needs more discussion.

73, de Lou K2LKK



Louis Kim Kline
A.R.S. K2LKK
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