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Author Topic: desktop coax switch help  (Read 734 times)
KB4OIF
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Posts: 181




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« on: August 03, 2019, 04:45:07 AM »

Good morning.  I need suggestions for a coax switch or other device.  I have limited space on my desk.  I have to reach thru my shelf to get to my coax feed thru to attach or unattach my coaxes during storms.  I have short arms and I am of larger stature.  Too much work to unload and move the desk out enough and I am in a small room. 

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KS2G
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Posts: 1072




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« Reply #1 on: August 03, 2019, 05:40:43 AM »

I need suggestions for a coax switch or other device. 

Alpha Delta Coax Switches DELTA-4B
https://www.dxengineering.com/parts/alf-delta-4b

Alpha Delta Desktop Coax Switches ASC-4B/N
https://www.dxengineering.com/parts/alf-asc-4b-n

Both have a front panel removable arc-plug surge protection module and a "center off" position that grounds all inputs.

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W5CPT
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Posts: 812




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« Reply #2 on: August 03, 2019, 07:38:21 AM »

I concur with the above. I went through two remote switches and moved my switching inside due to crosstalk. I had an older rotary switch that was not much better. I remembered that while a technician in the Army we used Alpha Deltas and had NO trouble with them. I got one and put all my switching problems away. 
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KB4OIF
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Posts: 181




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« Reply #3 on: August 03, 2019, 09:54:07 AM »

OK.  I actually have a 4B that I purchased a while back.  I have 2 HF antennas at present but will have 3 when our florida weather cools down some.  I run a Flex 6600M  as the main radio.  My mind is saying how are you going to do this.  2 inputs coming in from outside THRU the window feed thru from MFJ.  How do I attach the switch to the Flex and the antenna leads from the feed thru.  There are 5 females on the switch with the center one being the common one.  Have looked at it for quite a while and it still is not computing in my brain.
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K7JQ
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Posts: 1282




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« Reply #4 on: August 03, 2019, 10:11:22 AM »

OK.  I actually have a 4B that I purchased a while back.  I have 2 HF antennas at present but will have 3 when our florida weather cools down some.  I run a Flex 6600M  as the main radio.  My mind is saying how are you going to do this.  2 inputs coming in from outside THRU the window feed thru from MFJ.  How do I attach the switch to the Flex and the antenna leads from the feed thru.  There are 5 females on the switch with the center one being the common one.  Have looked at it for quite a while and it still is not computing in my brain.

You just want to switch the antennas to the Flex? The common (middle one) goes to the Flex, and pick any two of the other four females for your antennas. The open connectors are grounded if not used. You mentioned the Flex is your "main" radio. If you also want to switch the antennas to another radio, you'll need another switch.  BTW, if you're concerned about lightning, disconnecting the antennas in the shack is a bad idea. They should be disconnected outside.

73, Bob K7JQ
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KB4OIF
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Posts: 181




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« Reply #5 on: August 03, 2019, 12:11:06 PM »

I did not mention that I am running an amp.  SPE Expert 1.3 K.  Sorry.  Sorry been programming HT's for about 2 days now and my mind is fried.  It is also 73 yrs old. 
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K1VSK
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Posts: 529




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« Reply #6 on: August 03, 2019, 02:23:21 PM »

OK.  I actually have a 4B that I purchased a while back.  I have 2 HF antennas at present but will have 3 when our florida weather cools down some.  I run a Flex 6600M  as the main radio.  My mind is saying how are you going to do this.  2 inputs coming in from outside THRU the window feed thru from MFJ.  How do I attach the switch to the Flex and the antenna leads from the feed thru.  There are 5 females on the switch with the center one being the common one.  Have looked at it for quite a while and it still is not computing in my brain.
measure which connector corresponds to switch position as you cycle through the 5 positions using a multimeter.
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K0ZN
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Posts: 1858




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« Reply #7 on: August 03, 2019, 09:09:52 PM »


 IMPORTANT !!   HEED what K7JQ said:  You want to disconnect and ground the coax from the antennas OUTDOORS.....otherwise a lightning hit will follow your coax directly into your shack and destroy your radio and heaven knows what else inside your house. The last thing you want to do is provide a path for lightning into your house! (Be sure to devise a way to keep the ends of the coax dry or sealed from water.) To wit: your primary ground point for your antennas should be outdoors.

  73,  K0ZN
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KB4OIF
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Posts: 181




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« Reply #8 on: August 04, 2019, 03:45:58 AM »

I have two 20 foot long copper pipes that at down in the ground way into the water table. They are connected with 1 inch braid with grounding clamps. It then goes from one of the pipes to the window feedthrough using 1 inch braid. That length is about 3 feet. 
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WA8JNM
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Posts: 213




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« Reply #9 on: August 04, 2019, 01:03:57 PM »

Hope this question doesn't hijack the thread.  I routinely disconnect outside, just throwing the 300 ohm twin lead transmission, which WAS in the house and attached to the shack tuner, onto the grass 2o feet or so from the house. Isn't that sufficient?  Wouldn't attaching it to a TRUE ground outside the house make it MORE likely to induce a direct lightning strike to the doublet?
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KS2G
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Posts: 1072




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« Reply #10 on: August 04, 2019, 01:56:27 PM »

Hope this question doesn't hijack the thread.  I routinely disconnect outside, just throwing the 300 ohm twin lead transmission, which WAS in the house and attached to the shack tuner, onto the grass 2o feet or so from the house. Isn't that sufficient?  Wouldn't attaching it to a TRUE ground outside the house make it MORE likely to induce a direct lightning strike to the doublet?

Grounding and Bonding for the Radio Amateur
http://www.arrl.org/shop/Grounding-and-Bonding-for-the-Radio-Amateur/
$22.95 plus shipping
"Grounding and Bonding for the Radio Amateur" shows you how to make sure your station follows current standards for lightning protection and communication systems, not to mention the National Electrical Code. [emphasis added]

 Wink
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KX2T
Member

Posts: 1068




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« Reply #11 on: August 04, 2019, 05:35:25 PM »

I have had a few remote switches in the past few years, the first was an Ameritron RCS10, yes you only needed 3 to 4 wires for the control wire but the cross talk on that switch at best was maxed out at 40db, the second switch was the RCS4 that needed no control cable, here again very convenient but the cross talk was maybe 30db at best. I was all set to buy one of either the Array solutions or DX Engineering switches for between $400 to $600 investment but moving down to the lightning capitol of the USA I  went with the Ameritron RCS8 which  has decent cross talk  specs at 60db plus the sell either part just in case lightning hits and toasts the outside switch, it uses 6 conductor cable and you can run Cat5E for that plus at under $200 as long as the soldering is good your good to go. I have had the 4 position Alpha Delta's get a little quirky after continuous use so I prefer the remote system.
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