Hi Jim,
Thanks for your suggestions. Regarding the ceramic vac relays, do you use
Jennings, Kilovac, or another manufacturer's relays?
Are the HV DPDT mechanical relays open-frame relays? Is there a manufacturer
that you like?
73, Rich, N6KT
From: Jim Thomson <jim.thom@telus.net>
To: towertalk@contesting.com
Sent: Friday, May 4, 2018 8:46 AM
Subject: [TowerTalk] Coax Lengths for Stacked Yagis
<towertalk@contesting.com>
Subject: Re: [TowerTalk] Coax Lengths for Stacked Yagis
<I to am a supporter of having the phase box at the base of a tower. I am also
subscribe to the notion of feed lines especially after a switch box/phase box
be ODD multiples of ? wave
<Obviously taking the velocity factor into account. There has been more then
one occasion where a phase box got hot switched and had to be changed out in
the DARK.
<Wayne W3EA
## This is why I use ceramic vac relays. Then the relays can go anywhere on
the tower, like at the midpoint of a stack. Hot switch all you want. But
they can also be set up so
they cant be hot switched... like by using a break before make type of
rotary switch in the shack that controls the various relay configs.
## Ceramic vac relays can also be used in plane jane remote switch boxes, like
1-4 yagis, different bands etc, on a mast. Remote switch box located on mast,
then only 1 rotor
loop required. Zero issues with moisture. Then you can save coax..which is
what I thought was the idea behind a remote switch box in the 1st place ? If
using mech relays,
the HV DPDT types, with contacts in parallel, will provide for redundant
contacts..and also double the current rating.
## But ceramic vac relays are not cheap.... nor are HV DPDT mech relays.
I put the ceramic vac relays inside a gasketed water proof fiberglass nema
box, then also included
some silica gel...aka dessicant, and also a bit of heat, via
paralleled..redundant metal finned resistors, like the arcol brand, made in
the UK. No moisture ingress. Unused ports
are DC grounded.
Jim VE7RF
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