[TowerTalk] Building a "little pistol" contest station and theC-31XR

[Jim Lux]

At 09:22 AM 10/6/2006, Al Williams wrote:
>I had planned on using the C31XR with separate feedlines in a SO2R operation
>and then became concerned about how badly the close proximity of the
>elements would cause interference to the second rig and maybe even burn out
>the front end.
>
>I have all band Dunestar filters but was concerned about if the filter was
>accidentally switched out during the frenzied contest.
>
>EZNEC showed that the coupled signal could be quite strong on the adjacent
>elements?

And even with the filters, you're putting a pretty healthy out of 
band signal into the victim receiver.

The other issue would be the spurious output from the transmitter 
that's on one band that spreads into the adjacent bands.  Say you're 
putting out 100W on 15m, and the transmitter has (legal) spurious 
levels of -40 dB on the adjacent band.  That's +10dBm, in band, so 
the receiver filter won't filter it out.  If you had filters on both 
Tx AND Rx, it would probably help (-40 dB down spurs - 40dB for a 
filter is spurs down 80 dB at the tx antenna, probably another 20dB 
down into the victim receiver.. that's starting to be reasonable, 
although I hope you weren't planning on digging out S-0 signals on 
the other reciever)


>k7puc
>
>
>----- Original Message -----
>snips
> >From: "Andrew Roos" <Andrew.Roos at poynting.co.za>
> > My "Mark 1" station will be the C-31XR at 70 foot, with wire antennas on
> > 40 and 80m, without SO2R capability.>
> > To use the C-31XR with three separate feedlines,
> >
> > (a) Do I simply need three baluns, or is there something else I should
> > order.
> > (b) Do I need to order the C-31 specifically for three-feed operation,
> > or do I just order a "standard" C-31?
> > (c) How easy/hard is it to convert between one and 3 feedlines once it's
> > on a tower? I imagine this may be hard, so I should probably use three
> > feedlines from the outset, even if I don't have the band filters and
> > second radio for SO2R.
> >
> > Andrew ZS6AAA (ex ZS1AN).
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Andrew Roos
> > Poynting Antennas
> >
> > Telephone (011) 262-5155
> > Facsimile  (011) 262-5156
> >
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
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