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Author Topic: Amplifiers & Antenna switches  (Read 1701 times)
KT0DD
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Posts: 451




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« on: September 08, 2004, 08:45:52 AM »

Hello all, I have a Complete Ten Tec station with 2 amplifiers, a Hercules II SS for quick on and go applications, and a Titan I model 425 1.5 KW+ amp for DX work. I have all the INPUTS & QSK keying hooked up thru 2 switchboxes for fast switching between the two amps. However, I have kept the RF OUTPUT sides of the amps on pigtails only, and when I switch amps, I must unscrew one of the amps pigtail from the back of the antenna tuner, and screw the other amps pigtail into the tuner.

Before I re-arranged my radio desk, this was easy to do. Now that I have a new desk, and have re-arranged things, It's a bit of a struggle. I need to know if I were to put a GOOD 2KW+ rated coax switch on the antenna tuner input, and left both amps outputs hooked up to the switch, would there be enough isolation from the switch between the amps to prevent any damage between the two, especially at 1KW and above? I know keeping things physically separate as I was doing is the best, but it is now quite inconvenient. Any and all advice is appreciated. 73, Todd - KT0DD
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WB2LCW
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« Reply #1 on: September 22, 2004, 08:57:16 PM »

Use a transfer type coax relay or manual switch!

This is special type that has four connectors on the back. when one amp is switched to the antenna the
other can be terminated into a dummy load.When you switch to the other amp the idle amp will be switched
to the dummy load.See the Dow-Key website for examples.

You may find surplus units on the web at Ebay,Surplus Sales of Nebraska, or Max-Gain systems or order from Dow-Key?
They are expensive costing $150 or more for a new one from Dow-Key.
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WB2LCW
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« Reply #2 on: September 22, 2004, 09:12:08 PM »



I forgot to add info to the previous post.


Use a transfer type coax relay or manual switch!

This is special type that has four connectors on the back. when one amp is switched to the antenna the
other can be terminated into a dummy load.When you switch to the other amp the idle amp will be switched
to the dummy load.See the Dow-Key website for examples.

These commercial switches have very high isolation 60-80db between sections


You may find surplus units on the web at Ebay,Surplus Sales of Nebraska, or Max-Gain systems or order from Dow-Key?
They are expensive costing $150 or more for a new one from Dow-Key.

You can make one with one or two high quality RF type relays like the ones in
 remote antenna switch boxes or good open frame relays with 20 amp contacts or even one 20 amp DPDT relay!

Hook up the swinging contacts one to each amp and the
stationary contacts will have to be wired crossover fashion with one to the Dummy load and the other to the antenna!
Check out the diagrams in the Dow Key website!
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