Antenna switch

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  • Updated 5 years ago
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Need some advice please. I have one antenna I use for transmitting and receiving on a Kenwood TS-590. I just bought a Flex 1500. I want to use the 1500 to find stations, then dial them in on the 590 and transmit. I would like to connect that antenna to serve both rigs. But I think I need to install an antenna switch that would protect the Flex 1500 when I transmit. Does anyone know of a switch that would safely work?
Thanks in advance for the help/
Photo of "OB"


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Posted 6 years ago

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Photo of K2CM


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You could probably use any high quality relay to connect the F1.5K to your antenna, then switch the F1.5K out when transmitting. An old Dow Key relay might work too.

The issue is timing. Regardless of the relay that you use, the relay must be switched prior to transmitting. The TS590 must have the capability to switch the relay, delay, then transmit. I am not sure if the TS590 can do this.
Photo of Greg


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This may be an option, or the DX Engineering RTR.

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Jerry Kenyon

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I have done this with my 1500 using a dow key relay. The problem I ran into was that the flex still received the transmitted signal and I heard it thru the speaker.
I was using a a grounding relay to ground the antenna into the flex. Unless you can also mute the audio at the same time it will be a real pain. I wish they would have thought of this, as a lot of people would like to use the 1500 as a separate receiver, and use their higher powered transmitters. Timing wasn't an issue with the relay I used. My Icom switched it fast enough every time.
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Thomas Masterson

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I use a Flex 1500 to receive and transmit with a 15 year old Ft 990 which has separate receive  RCA jack for an internal antenna switch to use a receive antenna or a receiver like a Flex 1500. All you need is to set the Flex to receive only in setup menu and connect the Flex antenna to the receive antenna port port back of your transmitter.
Problem #1 Hearing your transmit audio thru the speakers I could not eliminate it, tried all kinda of chokes. The solution is to kill the audio by a 12v NC relay that is activated by the accessory plug on the back of the radio (relay opens and kills the audio) worked great. You could also use a foot switch, the Heil staggered twin switch would work, one switch connected to PTT and the other to the audio cutoff relay.

Problem #2 When you release the mike you may hear a loud bark for a split second thru the speakers. The solution is to keep the audio cutoff relay closed for approx a 1/4 to 1/2 second,  I did this by adding a 25 ohm resistor in series and a 2000 mfd
capacitor  parallel to the o relay coil. it worked great.

1.  All parts can be bought at Radio Shack

2. You can change the delay to the relay by changing the capacitor size plus or     minus.

3.  If your radio does not have a separate receive antenna option you could do the same with a remote antenna switch.controlled by your radio. You want to delay the audio relay but not the T/R relay

4.  I do have to manually tune the transmitter, I guess you could do the same if you CAT control your radio

6. Killing just the ground to the speakers did not work

This is not high tech but it works, an easy way to transmit 100 watts plus with a Flex 1500 with any radio old or new

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K6NOK- Bill

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I have a Kenwood TS-590 and a Flex 6300 and use one antenna for both. I use an Alpha Delta Model Delta 2. It is an excellent high quality 2 position coax switch that grounds the unselected radio's coax line. I did add a heavy ground cable directly to the switch just to ensure that the best possible ground is applied to the unselected rig. Haven't had any problems so far. However, I make a point of not transmitting on the same frequency that the other radio is listening to, just to be extra safe. Alpha Delta products are available from DX Engineering. Good luck and be careful!

W6BWS - Bill
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Ken - NM9P

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I run an alpha-delta 4 position switch like that in order to switch between three HF rigs. I sometimes use DDUtil to slave my 1500 to my 6500 so I can monitor my audio for testing, and to switch and compare my TX audio between the two rigs. The signal from my 6500 is about S9+30 or 40 on the 1500 when transmitting with 100 Watts. I just need to mute the RX on the rig I am not using at the time. I am embarrassed to admit that I have even forgotten which rig I was supposed to transmit on and called a few lengthy CQ's into a shorted line with each rig. No damage. These are some pretty stout rigs. (Though I don't recommend doing this at home!)