[Elecraft] loss of RX sensitivity

[rich hurd WC3T]

I guess that’s the electronic equivalent of blowing through a tube to clear
the blockage.  :)

On Mon, Sep 17, 2018 at 01:44 Frederick Dwight <kl7cw at mtaonline.net> 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
>
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>
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-- 
72,
Rich Hurd / WC3T / DMR: 3142737
Northampton County RACES, EPA-ARRL Public Information Officer for Scouting
Latitude: 40.761621 Longitude: -75.288988  (40°45.68' N 75°17.33' W) Grid:
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