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Re: [TowerTalk] What relay do Ameritron and Array Solutionsuseintheir co

To: "jeremy-ca" <>, "Tom McAlee" <>,"W7CE" <>, <>
Subject: Re: [TowerTalk] What relay do Ameritron and Array Solutionsuseintheir coax switchs?
From: Jim Lux <>
Date: Sun, 13 May 2007 10:35:01 -0700
List-post: <>
Comments interspersed..

At 06:27 PM 5/12/2007, jeremy-ca wrote:

>$45 is obviously a rip off for that relay. Since Ameritron makes a big deal
>about selling any individual part Id start there to get a more realistic
>resale price.

I don't think $45 is the actual each price Jay sells them 
for.  However, it could well be a realistic cost for him to put one 
relay in a box and ship it.  Might be that 3 relays would also cost 
$45.  The realities of "spare parts sales" has been beaten to death 
on the forum.  It's an expensive service to provide for the seller, 
although some mfrs do "subsidize" it (but eventually, you pay, in the 
form of original purchase price).  Also, many mfrs only sell 
replacement parts if you own the original product (especially those 
that are subsidizing the cost stocking, shipping, etc. onesie-twosie 
parts orders).

>To find the source go to your local library and ask for the Thomas Register
>that covers the letter R. This is a reference book that cannot be removed.
>Make a list of the pertinent info from the relay manufacturers; then its a
>matter of detective work.

Both Ameritron and Jay use custom relays in their products.  They 
have enough voume to justify the order.

One can also find off-the-shelf relays that might be acceptable.  A 
custom relay gives you the opportunity to make it just like you want 
it: e.g. Form X contacts, coils wound like you want, pinout or 
terminal configuration like you want.  I personally find the 
Ameritron relays in the RCS-8V a bit shock sensitive, which is a 
problem in a portable installation (bumping the box hard enough will 
cause the armature to come off the bracket) but that would be no 
problem in a fixed install.

Then, there's some testing involved. Since very few mfrs rate their 
inexpensive power relays for their HF properties, you have to build a 
prototype, measure the properties, revise the design, etc. 
Furthermore, it's highly, highly installation dependent (are those 
relays being mounted in a metal box?  What about parasitic C to the 
case?)  What about parasitic C to the coil? RMS current 
handling?  Voltage ratings?  None of these will match the 60 Hz 
ratings in the datasheet.

If you're building a one-off for yourself, you might just build it 
once, and if works good enough, you leave it.  Maybe you don't care 
that the port-port isolation is different on each port?  Maybe you 
don't care that the parasitic C and L is different on each port, 
because you're running an autotuner anyway?  Maybe you've got the 
relay box in your shack, and if you fry a relay accidentally, you 
just move the cable to an unused port and go on.  Maybe you've got 
the relay box at the top of a 300 ft tower in a remote control 
installation, and it requires driving 5 hours just to get to the base 
of the tower.

Jim, W6RMK 


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