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[TowerTalk] RF/Ant relays selection criteria-prelimi

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Subject: [TowerTalk] RF/Ant relays selection criteria-prelimi
From: (Torres, Jose)
Date: Fri, 21 Nov 1997 02:54:00 -0800
 To All:

I am very happy to have this terrific tool available and to be a part of 
this great community - Radio Amateurs


Original posting follows:

Hi everyone!

Would appreciate advice on the SELECTION CRITERIA for relays to be used in 
the construction of an antenna relay box. I am into home brewing so not 
interested in of-the-shelve units.

The frequency range is that of amateur HF (160 - 10 meters) and max. legal 

73 de KP3G

Replies so far follows:

Hi,  I just built such a box;  got some dandy relays from Surplus
Sales of Nebraska.  They have quite a selection of REAL antenna
switching relays for open wire feeders,  which is what I use.
They have units with the proper spacing for 450 ohm twin line
and full power operation.  Now, if you are using and switching
coax,  I don't have any info.

73,  Jim, KH7M

Near as I can figure out, some relays are well suited for RF and
some only for DC or AC.  I have made a switch box for my 80 meter sloper
array, and used DPDT (had to switch the grounds too) relays with 12v coils
from Surplus Sales in Nebraska.  If you are looking for specific relays, and
no one else brings these up, then I can track down the price and address.
(I think they were about $12 each, and they certainly handle the legal
limit in power.  I also think the company has a web page.)

73, Dave Clemons K1VUT


     I chose these relays because I was making an antenna based on an
article by K3LR (I think it was in Sept. 1995 QST - about his 160 meter
array).  At that time I knew nothing about relays, so I asked him and went
with his suggestion.  They work fine.  I did not have a Surplus Sales
catalog at the time, but have since got one and I think it lists these
relays as being good for RF.  Of course, I still don't know how to identify
such a critter if I saw one - I just know what K3LR and the catalog said
would work!

     I guess none of this answers your real question!  Sorry.

73, Dave Clemons K1VUT

 I've built many antenna change over boxes, and I use
the heavy
relays from Radio Shack.  they have some nice 12 volt, enclosed relays
that work very well.

I home brew all my antenna switch boxes.  There are many DPDT 12V relays 
will work, including from Radio Shack.  I don't think I save any $, but I 
the configuration I want.  I like to have several antennas on one band with
the ability to switch in any combination from one to all.  I use a single 
12v relay with the 2 poles in parallel and wired so that the antenna is
grounded when not selected or when power is off.  I use 24 volts on the line
to overcome resistance and to provide positive switching.

I put everything in a cast aluminum box and mount it to a tower leg for good
grounding.  I am convinced this method has helped in the lightning 
area too.  Of course, I dont think it would do much in the case of a direct

Chuck, KZ5MM

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