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Subject: Phasing a C31XR and C3SS
Author: N2TK <tony.kaz@verizon.net>
Date: 16-Nov-2002 09:12:36
I have a C31XR at 82'. I have a C3SS at 41'. I have equal length Buryflex
going to both - 85'. I tried several iterations of adding coax to the C3SS
to see if I can get some gain on all 3 bands. Here is what I found out for
my situation.
- With equal length coax I did not see any stack gain on any bands.
- By adding the distance the driven elements that have the balun attached of
each antenna are from the center of the tower and multiply this by the
velocity factor of the coax, I get 62". I added a 62" piece of coax to the
C3SS. Now I see stacking gain on 10 and 20m - it varies from just noticeable
to 2 s-units. On 15m, there is negative gain when stacked- about 2-4
s-units.
- Tried different lengths of coax added to the 62" piece. I used 4"
increments up to a total of 82". 10m and 20m still showed some gain. 15m
just got worse. It seems the best gain was with a total length of 66" of
coax added to the C3SS. It was difficult to tell the difference between 4"
either way. Did a lot of running back and forth to the tower to change coax
jumpers.
- I wonder if the reason 15m shows negative gain is because on the C31 the
feedpoint is shorted together and on the C3SS the feedpoint is joined to the
coax with jumpers? Don't know if there is an easy way to do something
different to help 15m?
- I haven't tried something less than 62". Don't know if there is a length
that would benefit 15m.

At least I improved 10 and 20m. This will now allow me to improve my signal
on 2 bands and also allow me to have the beams in two different directions.
Even though I don't have gain on 15m, I can have the beams in two different
directions to quickly switch directions.

Tony
N2TK




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This Thread
  Date   Author  
16-Nov-2002 N2TK
16-Nov-2002 Guy Olinger, K2AV
16-Nov-2002 N2TK
16-Nov-2002 Guy Olinger, K2AV
* 16-Nov-2002 N2TK
This Author (Nov-2002)
  Subject   Date  
C3/C3S Mods? 25-Nov-2002
Phasing a C31XR and C3SS 16-Nov-2002
Phasing a C31XR and C3SS 16-Nov-2002
* Phasing a C31XR and C3SS 16-Nov-2002
Phasing C31 and C3SS 04-Nov-2002