[TowerTalk] Field Day

Jim Thomson jim.thom at telus.net
Mon Jul 3 12:13:39 EDT 2017

Date: Mon, 3 Jul 2017 06:52:42 -0700
From: Grant Saviers <grants2 at pacbell.net>
To: "towertalk at contesting.com" <towertalk at contesting.com>
Subject: Re: [TowerTalk] Field Day

<We (N7KE) haven't had the lack of interference others note re same band 
<operation on FD.  So am looking for ideas about what to chase or improve.

<Operating 2A on two separate generators - Honda inverter 1000EU, no 
<interconnections of stations

We experience lot's of buzz from cw into ssb, need to get as far up the 
band as possible.  Reverse also true.  About the same level of trouble 
as last year with the beams 75' closer together.

Tried a new vertical 40m dipole this year on ssb and noticed less 
problems, which was expected with the crossed polarization.

Any designs for 100w same band filters appreciated.

Grant KZ1W

##  band pass filters, each being 7000-7300, probably are not going to do much good,
if 2 x xcvrs used on the same band, say 40m cw..and 40m ssb.   Heres a thought though.
I see ICE and others make band pass filters for the warc bands, like 100 khz wide for 17+12M,
and only 50 khz wide for 30M band.    If they can make a 50 khz wide band pass filter for 30M
band, they, or somebody should be able to make any BW  filter you want.    IE:  say 7000-7050,
or  7000-7075  for  40m CW.... then  perhaps 7100-7300 for  40m ssb, or perhaps  7150-7300,etc. 

##  Or perhaps an LP filter  for 40m CW..with a sharp cut off at  whatever upper freq u want, like perhaps
7050, 7070, etc.    Then say a HP  filter, again with a sharp cut off, for  40M  ssb, like 7100 khz. 

##  6 or 8 pole xtal filters, custom made, might be of some benefit...on RX only. Same deal, like  7000-7070
etc, for cw....and something similar for 40m SSB.   But if the 40m  SSB station has broadband TX IMD,
the CW station  will still RX the imd,  but less of it. 

##  I believe a band pass filter is just a combo LP + HP filter in series.  Perhaps a bandpass filter for 40M
cw use, but with a sharper cut off for the LP filter portion.   And a band pass filter for 40M SSB, but with a 
sharper cut off for the HP filter portion.   Band pass  filters that would handle 100-200 w, with the above
narrow widths, might well chop off some of the broad band trash, hash, buzz, imd,clicks, etc on  TX. 

##  A stand alone, tunable high Q RX pre-selector might be of some benefit.   The TX imd on ssb, with the K3
running 100w out, will not be wonderful on the CW stations K3...on RX.   This is where you want  real low TX
IMD...on ssb....and no clix at all on cw. 

Jim  VE7RF

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