[AMRadio] T/R Switching


C.L. Mitchell rsq14adam1 at hotmail.com
Thu May 13 11:19:51 EDT 2010


In addition to Bob's system, I usually use a DPDT relay for the antenna relay.  The second set of contacts I use to ground the receiver antenna input during transmit.  Probably not an issue at low power like for the DX-60 but found to be a good safety at higher power.

 

73,  Mitch  K9PNP
 
> Date: Wed, 12 May 2010 17:09:02 +0000
> From: w6ref at comcast.net
> To: kf5ccn at arrl.net; amradio at mailman.qth.net
> Subject: Re: [AMRadio] T/R Switching
> 
> Hi Brian, 
> 
> There are several options. I use an old Dow-Key relay with my DX-60. It's powered from the accessory socket on the back of the DX-60 (117 volts, as I recall), and is energized when you rotate the function switch to AM or CW. 
> 
> Also, if you can't find a Dow-Key at a reasonable price you can build your own relay box. I used two 117V relays from Radio Shack. The first relay controls the antenna switching, and the other "unmutes" my receiver. The box also has three female coax connectors just like the Dow-Key relay (one connects to DX-60, one to your receiver, and one to your antenna). Check you receiver's schematic to find out what's required to "unmute" your receiver. If you leave the Receive/Standby switch in "Standby", your receiver's muting and unmuting can be controlled by the second relay. Your receiver's accessory socket should have pin-outs for that relay. In some receivers it's just a matter of completing a ground connection to "unmute' your receiver. Be careful, though...other receivers may require you to switch B+ voltage. 
> 
> In my set-up I use the Dow-Key to control my vintage CW station, and the home-brew box to control the two AM stations. 
> 
> Hope this helps! 
> 
> 73, 
> Bob 
> K6GCN 
> 
> ----- Original Message ----- 
> From: "Brian Zwiener" <bzwiener at sbcglobal.net> 
> To: AMRadio at mailman.qth.net 
> Sent: Tuesday, May 11, 2010 2:45:31 PM GMT -08:00 US/Canada Pacific 
> Subject: [AMRadio] T/R Switching 
> 
> I have Purchased a gem of a Heathkit DX-60 AM Transmitter.I was wondering if someone had a better idea that what I have for T/R switching. I need to use the same antenna with separate transmitter and receiver, and not have the transmitter power get in the receiver front end. If someone has an idea, schematic, or link I would appreciate it very much. I want to get this on the air soon and have fun. 
> 
> 73 Brian KF5CCN at ARRL.NET KF5CCN.COM NEW Ham Radio News Group 
> Life is much too short for QRP! 
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