The net started with a query that wb5vst, Ben, relayed to me on the March 10th RACES Net. He was interested in knowing how to go about hooking up several radios to the same speaker.
With four or so radios in his car and speaker space sparse, having the radios share a speaker would help him manage the available space. What he wants is the ability for one speaker to carry the signals from four radios all at the same time (as if you have four radios on). So a switched speaker system would not necessarily work.
On the RACES Net, kd5und, Travis, suggested a mini-mixing board. A mixing board would tend to isolate the signals from each other and send them to one speaker output.
To start things off on the Tech Net, ke5yoo, Mike, relayed some information he discovered that related to the last Tech Net on February 27th, regarding coax. There was an issue of how to use various types of coax. Mike mentioned that RG58 is not a very good coax to use. It's only good for about 150 watts of power on VHF. In addition, Mike told us that as the frequency goes down, all coax types tend to work better.
ke5zol, Casey, checked in and had a question about the performance of his station. He said that yesterday evening, he copied the RCWA Net quite well, but could not make it in from about 31st and Harvard. He is talking on 10 watts with a magnet mount antenna on a piece of sheet metal in his garage.
kc5wsi, Ray, replied that Casey's equipment performance was understandable and that it is really performing well. Getting into the RCWA repeater with that set up, that far away, is not likely. In fact, Casey is doing well to get into the BA repeater as well as he is. ke5omv, Don, agreed.
ae5ft, Gene, related to Casey that he had a similar set-up when he placed an ultra-light MFJ magnet-mount antenna upside-down on his ceiling vent. Gene went on to mention that with that set-up, at his location, he was able to get into all of the Tulsa area repeaters.
ae5fa, Rob, (regarding 4 radios/1 speaker) suggested that installing a 4 to 8 ohm resistor on the signal side of the audio line coming out of each radio and hooking into the speaker with the return lines (or shield) wired in common and to the shield side of the speaker may work to keep signals from back-feeding into the other radios.
ke5wsu, James, suggested using diodes instead of resitors.
ae4fa, Rob, mentioned that diodes would just "clip" the audio and it would not work well.
kb5vdb, Ron, said that he found a device that you can use to hook up 6 radios to one speaker in the AES catalog, but that it may not allow you to listen to all of the radios at once. The part number is NCS 3220.
wx5lib, Matt, said that he has used a commercially available product to hook up four radios to one speaker in emergency vehicles. It is called a 4-channel combiner amplifier. The website for that is: http://www.fleetradioproducts.com/htm/model301b.htm
kb5vdb, Ron mentioned that you could re-wire a quadrophonic headphone to allow for a 4-input headset.
kc5wsi, Ray, said he found the four into one device from AES and it is called an interface kit with catalog numbers 3240 and 3230.
kc5uoq, Larry, announced the Storm-spotter training in Claremore for March 17th.
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