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Author Topic: Antenna / Radio Patch Board  (Read 1145 times)

Offline ChrisSmolinski

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Antenna / Radio Patch Board
« on: April 12, 2018, 1942 UTC »
I finally built something I have been wanting for a while - an easy way to switch antennas and radio. I wanted something more flexible than the basic N position switch, which is great if you want to switch several antennas on one radio (or one antenna between several radios).  But how to switch multiple antennas and radio?

I considered (but quickly shelved) something using a matrix of switches or relays. It would be complicated, quickly get expensive, and not provide much isolation between antennas/radios.

I ended up with this, two rows of BNC bulkhead adapters, mounted on a 1/4" thick plywood panel, which is attached under part of the shack desk. Easy to get to, but mostly out of the way:



The first row is for the radios, the second for the antennas. Short (1.5 ft) BNC cables connect a radio to an antenna. I can easily switch which antenna is connected to a particular radio, as well as quickly unplug all of the antennas if a storm approaches.

I decided to use non conductive wood in place of metal, as I wanted to maintain the electrical separation of the various cables. I suspect metal could be used as well, if it was well grounded.   Actually, I think it is better to keep every run electrically isolated.

The metal box you see plugged into the beverage antenna connector is a homebrew low pass filter for longwave.

I have several unused BNC jacks, for future expansion.

Here's what a BNC bulkhead adapter looks like:


« Last Edit: April 12, 2018, 2046 UTC by ChrisSmolinski »
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
NRD 545 / netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 670 ft horizontal loop / 500 ft northeast beverage / 270 ft west-south-west beverage / 300 ft south beverage / 43m / 20m / 10m  dipoles / Crossed Parallel Loop

Offline pinto vortando

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Re: Antenna / Radio Patch Board
« Reply #1 on: April 13, 2018, 0855 UTC »
An economical alternative to a jumble of switches, etc.   :)
You may want to color code the jumper from the transceiver with tape so as to identify it such that it doesn't inadvertently get connected to one of the receivers  :o 
« Last Edit: April 13, 2018, 0912 UTC by pinto vortando »
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Offline ChrisSmolinski

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Re: Antenna / Radio Patch Board
« Reply #2 on: April 24, 2018, 1424 UTC »
Some updates to the patch panel, to reflect the addition of the 10m dipole and second beverage.  I also added a connection to the second RF input on the AFE822x SDR, for phasing, and re-organized some of the locations, for ease of use.

In hindsight, I would space the jacks a little further apart, although the current setup works, it can be a bit tight.

Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
NRD 545 / netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 670 ft horizontal loop / 500 ft northeast beverage / 270 ft west-south-west beverage / 300 ft south beverage / 43m / 20m / 10m  dipoles / Crossed Parallel Loop

Offline Josh

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Re: Antenna / Radio Patch Board
« Reply #3 on: April 24, 2018, 1901 UTC »
I contemplate a grounded aluminium board with multiple bnc (or perhaps f fittings) bulkhead fittings, and several cable tv splitters (one splitter feeding two to get the same signals to at most four receivers as inexpensively as possible) mounted on the backside to feed various sources to various receivers.
Conveniently located near Vincennes Indiana.

Offline ChrisSmolinski

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Re: Antenna / Radio Patch Board
« Reply #4 on: April 24, 2018, 1925 UTC »
I contemplate a grounded aluminium board with multiple bnc (or perhaps f fittings) bulkhead fittings, and several cable tv splitters (one splitter feeding two to get the same signals to at most four receivers as inexpensively as possible) mounted on the backside to feed various sources to various receivers.

Originally I was going to go with F connectors, but they're a pain to screw into the jacks. There's push on F connectors, but I am not sure how well they'd work.

I purposely avoided a metal board, to keep the grounds at the patch panel separate.

I do have a splitter I made for HF, I was contemplating installing it on the end of the patch panel. Right now it is in a small metal box, the same size as the LW low pass filter, it actually works OK that way as well, hanging in the air.
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
NRD 545 / netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 670 ft horizontal loop / 500 ft northeast beverage / 270 ft west-south-west beverage / 300 ft south beverage / 43m / 20m / 10m  dipoles / Crossed Parallel Loop

Offline pinto vortando

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Re: Antenna / Radio Patch Board
« Reply #5 on: April 24, 2018, 2343 UTC »
I contemplate a grounded aluminium board with multiple bnc (or perhaps f fittings) bulkhead fittings, and several cable tv splitters (one splitter feeding two to get the same signals to at most four receivers as inexpensively as possible) mounted on the backside to feed various sources to various receivers.

An inexpensive hardware store variety TV splitter will have about 3.5 db of loss per split.  Therefore, to split a signal once then each again to feed 4 receivers would mean there would be 7 db loss at each receiver.  This may be OK for a cable TV or a strong OTA application but not suitable for weak signal work. 
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Offline pinto vortando

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Re: Antenna / Radio Patch Board
« Reply #6 on: April 24, 2018, 2353 UTC »

Originally I was going to go with F connectors, but they're a pain to screw into the jacks. There's push on F connectors, but I am not sure how well they'd work.


Quality BNC and F connectors are each typically rated for 500 operations.  The key word is "quality". 
Otherwise  RG-6 is as good or better than most types of commonly used Ham radio coax as far as loss specs are concerned and a lot less expensive.  The F connector is easily installed with no soldering required. 
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Offline redhat

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Re: Antenna / Radio Patch Board
« Reply #7 on: April 25, 2018, 0424 UTC »
Generally, CATV hardware (splitters, amps) provides little use below its cutoff frequency of around 40 MHz.

I would have used a 2U metal rack panel with D cutouts, and used insulated jacks.  For DC protection against lightning, small shorting switches can be placed across the lines coming in.

https://www.markertek.com/product/16x/connectronics-punched-unloaded-16-point-d-series-xlr-rack-panel-2-ru

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Offline Josh

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Re: Antenna / Radio Patch Board
« Reply #8 on: April 25, 2018, 0553 UTC »
I contemplate a grounded aluminium board with multiple bnc (or perhaps f fittings) bulkhead fittings, and several cable tv splitters (one splitter feeding two to get the same signals to at most four receivers as inexpensively as possible) mounted on the backside to feed various sources to various receivers.

Originally I was going to go with F connectors, but they're a pain to screw into the jacks. There's push on F connectors, but I am not sure how well they'd work.

I purposely avoided a metal board, to keep the grounds at the patch panel separate.

I do have a splitter I made for HF, I was contemplating installing it on the end of the patch panel. Right now it is in a small metal box, the same size as the LW low pass filter, it actually works OK that way as well, hanging in the air.

Good points there, the feeble center conductor in a typical f con rules it out for me. A friend made a panel looking very similar to yours, but with slip on uhf cons, works fine.
Conveniently located near Vincennes Indiana.

Offline Josh

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Re: Antenna / Radio Patch Board
« Reply #9 on: April 25, 2018, 0554 UTC »
I contemplate a grounded aluminium board with multiple bnc (or perhaps f fittings) bulkhead fittings, and several cable tv splitters (one splitter feeding two to get the same signals to at most four receivers as inexpensively as possible) mounted on the backside to feed various sources to various receivers.

Some of them go down to the ambc band without too terrible loss, most are rated to 5MHz at least anymore they are. I have a handful so will do some testing to see what's what.
An inexpensive hardware store variety TV splitter will have about 3.5 db of loss per split.  Therefore, to split a signal once then each again to feed 4 receivers would mean there would be 7 db loss at each receiver.  This may be OK for a cable TV or a strong OTA application but not suitable for weak signal work.
Conveniently located near Vincennes Indiana.