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echo: ham_tech
to: ED KRISTON
from: ROB DENNIS
date: 1997-12-07 23:19:00
subject: In Attic Dipole

 RD>> Recieve was great on 160 to 20m but when it came to
 RD>> transmit it was a bit of a bear to get it to tune on 80m
 EK> At present, this is the same problem that I am having.  The bandwith
 EK> when the antenna is adjusted has a really sharp drop off.  Move the freq
 EK> only a little and major retuning is required.  It will load on a
 EK> frequency, I made a little cheat sheet to help with base adjustments
 EK> when changing bands.  This has made it a lot easier.
 Having the cheat-sheet for the tuner helps Ed,but maybe it is the space 
constrictions and the 10m dipole being in amongst the elements of the G5RV?
 What about a wire loop running along just under the eaves-troughs outside?
 Do you have enough space to hide one up there and not have it noticed?
 What are you feeding the G5RV with for feedline? (co-ax or ladderline)
 RD>> This same idea can be used in an attic but tack the zig-zag `legs' to
 RD>> the truss beams in the roof with the PL connector hanging at the centre
 EK> I think this is do-able.  Presently the installation of the G5RV (105')
 EK> resembles a flat top and two j's.  It looks something like this:
 EK>                      ________________________________
 EK>                      |                              |
 EK>  O=AR270 dual        |  O   ____10_M__dipole____    |
 EK>    bander            |             _________________|
 EK>                      |_ Ladder line
 Having that 10m dipole where it is may be part of the problem with the G5RV.
 Have you tried the G5RV without the 10m dipole in place?
 If so what happened?
 Having another dipole that close to one already in place,and essentially in
the middle of it,can cause some tuning and resonance problems on the lower 
frequency of the two if the dipole is cut for a multiple of one of the lower 
bands.
 Move the 10m dipole out of the way -then- set the G5RV up as best you can 
and put the 10m one back after you do some tests.
 EK> problems noted.  Only the G5RV is busting my stones.
 EK> I will problably try reinstalling the G5RV in the second style above and
 EK> move the 10M further up toward the peak of the roof.
 That may help. Getting the 10m dipole up out of the way of the HF one should 
help the tuning more on the G5RV and not be such a pain.
--- GoldED 2.42.G1219
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* Origin: VE3SJN....Moderator....HAM_TECH (1:163/506.4)

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