Date: Sun, 08 Aug 2010 10:44:45 -0400
From: "Joe Subich, W4TV" <lists@subich.com>
Subject: Re: [Amps] Automotive Relays
> Currently using an RCS-10, which can have up to 7 relays in the
> RF path. Will be interesting to see how it holds up.
Since the relays are arranged in a "tree" (one feeding two, each
of which feeds two more) there are always three relays in line to
each antenna. See: http://ameritron.com/man/pdf/RCS-10.pdf
73,
... Joe, W4TV
## per the manual, there is exactly 3 x relays, nose to tail, in the circuit
for any given ant.
That means BOTH the RX + TX on some ports, is passing through NC
contacts....that's a no-no..esp
with mech relay's in an outdoor environment. Strike-1
## the RCS-10 will handle 8 [eight] ants. They used a total of 7 relays do
accomplish this.
## NONE of the 8 ants have their center conductor's grnded, when not in use !
More fubar. Strike-2
## A better technique would be to use 8 DPDT relays. Parallel all the
contact's. Now you have some redundancy.
Each ant port goes to the COM of it's own, dedicated relay. NC contact goes to
grnd buss. NO contact goes to
hot kw TX/RX main input buss.
## Ok, now with the above config, ALL DE-energized relay/ant port's have
their center conductor's grnded...and right
at the top of the tower. NO ant port ever gets connected to the input via NC
contact's ! For added measure, you could
add one extra SPDT-NC relay, and wire it between grnd + INPUT connector. Then
during any thunderstorm activity, and
all 9 relay's DE-energized, not only are all 8 ants grnded at top of
tower, but the input is also grnded..at top of tower. A gas
discharge tube on the input side of the box should also be used.
## the above box is how my Array solutions 20 kw rat pack came wired. They
used DPDT-20A relays, with 20A contacts,
and all contacts in parallel. 10 kv between any contacts, or contacts to
armature/grnd. The 7-16 Din connector's I asked for,
have a 4.5 mm gap between OD of the 7mm female inner tube and the 16mm ID of
the outer tube. [16-7= 9mm. 9/2=4.5mm]
4.5mm = aprx 6300 v break down. You can get em in up to 12 positions. This
box I have has no pc board traces at all. They
used 3/4" wide Cu strap for both the NC grnd buss, and also the NO hot
buss... and 5/16" spacing between em. This results
in a 50 ohm strip line. Flat swr from 160-6m. Mine came in a die-cast al
box.
## I added up what 7 connector's + 6 relays would cost, box, etc, and decided
this was one item I was not going to hb for a change.
There is no reason why you couldn't hb one of these things. I have also seen
them using P+B DPDT power relays, with 30A contacts,
again, with all contacts in parallel. To eliminate/minimize any contact
issues, I re- silver plated all the contacts with the cool-amp goop.
I then apply a thin coat of ..'conducto-lube' to all contacts. That stuff is
just pure silver powder, suspended in grease.
http://www.cool-amp.com/ I also had all the cu strap inside the box
silver plated.
I use 2 resistor's in parallel, to add heat inside the box. [ gold/metal
finned dale type], again for redundancy, and also installed a bag
of desiccant [silica gel]. The resistor/silica gel idea is also used on my
nema box's, used for other stuff. This is as good as I could
get it to my liking. Another method is to use SPDT vac relays..instead of
DPDT mech relays... like Gigavac GH-1 G-2... or
Jennings's RJ-1A / RJ-2B / C. ..or kilovac eq. I use vac relay's for all
the BIP/BOP box's I design for friends. Then they are
110% bullet proof. There is no reason a SPDT relay [with all contacts in
parallel] would not work for a simple BIP/BOP box.
We gave up on the top/bottom/BIP/BOP circuit..and just use the BIP/BOP config.
The BIP/BOP box's I cooked up use a
simple LC config,with just a mess of NPO caps to grnd on the input... and a
series CU tubing coil to output. The LC box is used
for any 2 stacked yagi set up.[25 ohms output]... and also the 3 x yagi
setup [16.67 ohms output]. This is for monoband ant's only.
BIP/BOP box's used only on 40m and 6m..in most cases.
later...... Jim VE7RF
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