Transmitting can burn out all those tiny diode junctions formed by joints in
the tower etc. They grow back and bring back the spurs with them.
Transmitting at higher power generally increases the time it takes for them
to grow back. Another reason life is too short for QRP. Before a 160m
contest the band can be pretty full of these products. They disappear after
transmitting. After the contest ends it's usually Sunday afternoon before
they start coming back....... .
73 Don
VE6JY
> > > I installed a new 75 meter delta loop on Tuesday. Its 265 feet
> > >total length, cut for 3.795 khz. SWR is acceptable, less than 2.0
> > >to 1 on that freq.
> > >
> > > Problem is that when using this antenna I have a spur or
> > >harmonic every 10 khz across the 75 meter band. All the way from
> > >3500 up to 4000 the spur can be heard every 10 khz starting
> > >exactly on 3.500, in the DX window 3770-3780-3790-3800 the
> > >sput peaks at about 30 db over S9. All connections on the
> > >antenna, coax and fittings check solid.
> > >
> > > The delta loop is hung from the top of a 80 foot tower that also
> > >has a HyGain TH11 and Cushcraft 402CD on it.
> > >
> > > Weird thing is that if I key the transceiver (TS-940SAT) the spur
> > >will go away for about 2 seconds and then returns again.
> > >
> > > OK you list guru's.....what are your ideas and suggestions, this
> > >one has me stumped. Any suggestions on how to find the source
> > >and cure this problem would sure be appreciated....
> > >
> > >Bryan W5KFT
> > >
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