Good points Bob.
Remember, HAND tightening of PL259's is NOT sufficient,
especially where temperature variations are prevalent.
Another place to check for a tight connection is the screws
that connect the driven element ends to the feedline.
Tom N4KG
On Sat, 9 Nov 2002 "Robert Shohet" <kq2m@earthlink.net> writes:
> On occasion I have had similar problems with one of my 40-2cd's at
> 123'.
>
> I believe that it is because I did not originally open up the traps,
> replace
> the (most likely) rusted aluminum screws and reseal. I had
> significant
> RF problems in 2 contests with fluctuating SWR and audio, RF in the
> shack,
> etc.
> I am only 20 miles from Long Island Sound (a very, very large body
> of salt
> water)
> and you can see it from the top of my tower. I have found
> significant
> corrosion on many relay
> boxes outside - no doubt from the rain/snow in coastal storms which
> comes in
> from the
> Atlantic and LI Sound.
>
> I am sure that corrosion is that problem here and with your QTH on
> salt
> water, that
> makes it even more likely as your culprit too.
>
> However, before you assume that it is the feedpoint, check the PL259
> and
> where it is connected
> on the end of the coax coming down from the tower.
>
> In another contest, I had an intermittent with the same 40-2cd and
> it turned
> out that the
> large temperature changes over a few months caused the PL259 to
> loosen
> slightly
> and then arc with 1500 watts going through it. This caused the
> intermittent
> and there was
> a black carbon buildup on the PL259 and the SO239 where it was
> connected.
>
> Cleaning off the carbon and screwing the PL259 on with a large
> wrench
> cleared up
> that problem.
>
> Try the simple (and not so obvious) fixes first.
>
> GL!
>
> Bob KQ2M
>
> > On 40M, which is usually my best band here on the ocean, I started
> > having intermittent spells of signal masking. All signals would
> > suddenly drop about 3-4 S units with a slight noise mask and then
> > reappear normally after an interval of 45 seconds to several
> minutes. I
> > decided the FT1000MP was the culprit, so took it out of the line
> and
> > replaced it with the FT-1000D. Problem persisted. Took the
> ATR-30
> > antenna tuner out of the line thinking perhaps the antenna switch
> was
> > the problem (Use the tuner to reach the SSB part of 40M). Still
> > persisted. Then I noticed that the SWR on the 402CD was
> fluctuating
> > from 1:1 up to 3:1 that appeared totally random. No wind, so the
> 402CD
> > was perfectly still. I Run the radios barefoot on 40 and 80. Too
> much
> > RF in the media room next to the shack to run HP, not to mention
> setting
> > my alarm system off every few minutes.
> >
> > Background. I recently rebuilt the 402CD after a tropical storm
> took it
> > down last fall. Mostly new aluminum, applied the Leesom upgrades,
> and
> > installed new coax (9913) feed line. I suspect a corroded feed
> point
> > connection even though I just put the antenna up several months
> ago with
> > liberal applications of coax seal, etc. I did put in a few
> > strategically placed aluminum rivets in the elements, and four SS
> screws
> > in the tips. (High winds here sometimes blow the tips out of the
> > elements.)
> >
> > Any suggestions or ideas before I tackle rebuilding the feed point
> on
> > the 402CD which is way out there. I did put it up with an extra
> TH-7DXX
> > mast to boom clamp which will let me tilt the boom down so I can
> reach
> > it.
>
>
>
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