I used that trick to keep my DSL line running for a couple of years when
Verizon was abandoning copper and no longer interested in doing
maintenance. Placing a resistor across the telephone line would draw a
constant small current, not enough to off-hook the line but enough to
"seal" the poor connection, wherever it was, and improve the noise margin.
Regarding the PL-259 center pin-- it's also important to check the
connection between the threaded shell and the body of the plug. That is
a common and overlooked connection point subject to poor connection.
Note that there is no electrical connection through the threads on the
plug body and the threads on the shell; these threads are merely a stop
to keep the shell from sliding down the cable when not connected to the
SO-239 on the equipment.
The electrical connection occurs through the lip at the back of the
shell which butts against the threaded region on the plug. The area of
this thin ring of contact is pretty small so it's important that the
mating surfaces are entirely clean and free of corrosion.
It may help to disconnect the cable, then hold the back of the plug in
one hand (where the cable enters it), then pull on the shell with the
other hand, toward the pin end, as if trying to pull it off the plug;
while maintaining this pressure, twist the shell vigorously. That will
help clean the mating surfaces, especially if the plug is not silver
plated but that cheap "shiny metal" stuff a lot of plugs have now. Also
do this with all jumpers between SWR meter, matchbox, etc.
73,
Drew
AF2Z
On 09/17/18 01:44, Frederick Dwight wrote:
Scott,
The problem you describe is actually quite common in electronics. In the
telephone industry, especially in the “good old days” with wire cables,
sometimes with many splices it was common to get drop outs. These could be due
to a splice, wire wrap connection, oxidized relay contact or whatever,
especially with only low level signals. If the circuit also had a DC voltage
on it, the problem often did not exist. In fact it was common on critical
circuits for the FAA or military, or whatever to sometimes just put “sealing
current” on certain circuits just to be sure it was reliable. Often we used 24
volts DC or less with only a few ma of current. At one time I had many phased
verticals which were controlled by many relays. Occasionally the received
signal would drop by many S units. Sending a single dot, even with QRP or QRPP
power always cleared the problem, sometimes for weeks or months. So it could
be a connection in the antenna system, a plug on a circuit board, or even a
relay. I have never experienced trouble with Elecraft relays personally.
Sometimes PL-259 center pins are not correctly soldered, and can present
similar symptoms. You could try a random wire, or even something like an 80
meter dipole on 30 meters, just to see if it was anywhere in the antenna
system. Even a volt or two is often enough to punch through a poor solder or
oxidized connection, but even something like a 0 dBm signal is just not enough.
I have identified problems with BNC connectors and adaptors purchased at ham
flea markets which are just not reliable and are probably factory rejects. So
look into your antenna system before you dig into your rig. You could also
hook a signal generator to the rig and see if it receives OK on all bands with
something like less than an S9 signal. Be sure to not transmit into your
generator, and/or set your tx to very low power. Good Luck Rick KL7CW
Sent from Mail for Windows 10
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to pu...@af2z.net
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com
