[TowerTalk] Coax Lengths for Stacked Yagis
n6kt1 at sbcglobal.net
Fri May 4 12:15:01 EDT 2018
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 at telus.net>
To: towertalk at contesting.com
Sent: Friday, May 4, 2018 8:46 AM
Subject: [TowerTalk] Coax Lengths for Stacked Yagis
<towertalk at 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.
## 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.
TowerTalk mailing list
TowerTalk at contesting.com
More information about the TowerTalk