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Author Topic: vhf/uhf remote antenna switch  (Read 1254 times)
K3YE
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« on: October 06, 2007, 06:18:39 PM »

i'm installing a new antenna complex some distance from house: multiple (horiz & vert) 6m, 2m, 70cm & 1.2 antennas. i want remote antenna switch at pole to run two good coaxes to house. all the switches i've found so far are "rated" only for HF or up to about 150mhz. are there any rated to 70cm? 1.2 ghz? with n-connectors? or does the "rated" spec mean nothing & i can use with whatever freq?
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K9KJM
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« Reply #1 on: October 06, 2007, 08:07:37 PM »

How far is this antenna complex away from your house, and what do you call "good" coax?

At 1.2Ghz, I would only consider something like  
1 5/8" Heliax for any run longer than 50 or so feet......
Even 432Mhz needs high quality coax feedline to be kept as short as possible.  
Then the coax switch itself will introduce some loss no matter how high a quality it is, And you DO need a good one for two meters and higher.  A good used military switch with type "N" connectors is what you really need. Better yet, Spend that money on some good used Heliax (Now that cellphone sites are starting to upgrade, 1 1/4" and 1 5/8" Heliax are starting to come on the used market at very good prices) OR some cable TV trunk line "spool ends"
Better yet, Figure some way to move the shack closer to the antennas, Or the antennas closer to the shack.
When you check out the prices of really good quality remote switches, You could buy lots of good used Heliax and run dedicated coax runs for each antenna and not have switch problems in the middle of winter or some such........
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K3GM
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« Reply #2 on: October 06, 2007, 09:37:32 PM »

I have used a surplus Transco 4 port coaxial switch.  It features N connectors and it powered by 24 volts.  I checked the insertion loss at my lab in work and the attenuation was extremely low at 2m and 70cm, on the order of a few tenths of a db.  They are frequently found at hamfests, and on ebay.
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WA3SKN
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« Reply #3 on: October 08, 2007, 05:39:59 AM »

This depends on how much of an "impedance bump" you are willing to have.
Most of the 150 Mhz switches can work up to about 300 Mhz.  You will probably want something special for 400 Mhz and above.

-Mike.
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WB2WIK
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« Reply #4 on: October 08, 2007, 09:27:21 AM »

>: vhf/uhf remote antenna switch  Reply  
by K3GM on October 6, 2007  Mail this to a friend!  
I have used a surplus Transco 4 port coaxial switch. It features N connectors and it powered by 24 volts. I checked the insertion loss at my lab in work and the attenuation was extremely low at 2m and 70cm, on the order of a few tenths of a db. They are frequently found at hamfests, and on ebay.<

::Bingo!  These are the right kind of remote switches to use at 70cm and 23cm.  Transco made many models for many years which are absolutely lossless up to about 6 GHz.  "The few tenths of a dB" measured by K3GM was likely in his cables or just measurement error...I've measured all my Transco remote switches at 0.05 dB or less at 1.2 GHz, once the patch cable loss was removed from the formula.  They are perfect, weatherproof, and very expensive "new" but a great deal "suplus" and most are indeed 24 Volts DC powered.

WB2WIK/6
 
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