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Author Topic: Mobile Radio Audio Combiner  (Read 1405 times)

N2AYM

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Mobile Radio Audio Combiner
« on: June 17, 2019, 12:28:19 PM »

Does anyone make an audio combiner like the
Fleet Radio Products 4 port combiner they used
to make? I did the google & bing search with no
real usable hits.
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KB8VUL

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RE: Mobile Radio Audio Combiner
« Reply #1 on: June 20, 2019, 04:42:25 AM »

What are you trying to do?
If you are looking to feed several radios into a single speaker, it's really not that hard.
You would need to build a Mixer of sorts.  Each input would need a simple voltage divider network consisting of a 8 to 15 ohm resistor across the input, with a 1K or 1.5K tapping the audio off, into a 1K pot.  Pull all the centers of all the pots off to a common point and feed that into a small car audio amp and connect a speaker to that.

You could eliminate the 1K pots and just connect all the voltage dividers together but the pots let you do some matching. 
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N2AYM

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RE: Mobile Radio Audio Combiner
« Reply #2 on: June 20, 2019, 08:17:57 AM »

What are you trying to do?
If you are looking to feed several radios into a single speaker, it's really not that hard.
You would need to build a Mixer of sorts.  Each input would need a simple voltage divider network consisting of a 8 to 15 ohm resistor across the input, with a 1K or 1.5K tapping the audio off, into a 1K pot.  Pull all the centers of all the pots off to a common point and feed that into a small car audio amp and connect a speaker to that.

You could eliminate the 1K pots and just connect all the voltage dividers together but the pots let you do some matching. 


I am not trying to do anything - asking cause where i work (we service various Depts involving EMS/FD/PD)
and many ask for multiple radios to all use one speaker as the device i referred to used to do but it is not
made anymore.
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W9FIB

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RE: Mobile Radio Audio Combiner
« Reply #3 on: June 20, 2019, 09:11:18 AM »

When I built our county portable multi radio cabinet for field interfacing multiple channels, I did basically what VUL said except I did the mixing with a small PA mixer with a built in amplifier. It was a 1U 19" rack mount cabinet. I just built the radio speaker output cable for each radio with the voltage divider as part of the patch cable. Worked like a charm with very little effort or expense. Good audio quality and easy control. Plus being made by Shure, it was built like a tank. And if it ever died for some reason, it was a standard product which can be swapped out in minutes.

I did like having the control aspect as it was easy to mute any or all signals in my local speaker but yet not change anything going to the Harris interface controller.
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73, Stan
Travelling the world one signal at a time.

N2AYM

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RE: Mobile Radio Audio Combiner
« Reply #4 on: June 20, 2019, 09:55:32 AM »

When I built our county portable multi radio cabinet for field interfacing multiple channels, I did basically what VUL said except I did the mixing with a small PA mixer with a built in amplifier. It was a 1U 19" rack mount cabinet. I just built the radio speaker output cable for each radio with the voltage divider as part of the patch cable. Worked like a charm with very little effort or expense. Good audio quality and easy control. Plus being made by Shure, it was built like a tank. And if it ever died for some reason, it was a standard product which can be swapped out in minutes.

I did like having the control aspect as it was easy to mute any or all signals in my local speaker but yet not change anything going to the Harris interface controller.

You guys are not following me - whatever we buy has to be small like the Fleet Radio Products 4 port combiner so it can fit inside
either a havis or Troy console and not a bunch of parts that's cobbled together - local gov purchases and higher archy have some
requirements besides the common sense aspects of installing this inside a console.
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W9FIB

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RE: Mobile Radio Audio Combiner
« Reply #5 on: June 20, 2019, 05:48:25 PM »

When I built our county portable multi radio cabinet for field interfacing multiple channels, I did basically what VUL said except I did the mixing with a small PA mixer with a built in amplifier. It was a 1U 19" rack mount cabinet. I just built the radio speaker output cable for each radio with the voltage divider as part of the patch cable. Worked like a charm with very little effort or expense. Good audio quality and easy control. Plus being made by Shure, it was built like a tank. And if it ever died for some reason, it was a standard product which can be swapped out in minutes.

I did like having the control aspect as it was easy to mute any or all signals in my local speaker but yet not change anything going to the Harris interface controller.

You guys are not following me - whatever we buy has to be small like the Fleet Radio Products 4 port combiner so it can fit inside
either a havis or Troy console and not a bunch of parts that's cobbled together - local gov purchases and higher archy have some
requirements besides the common sense aspects of installing this inside a console.

Sorry...I didn't realize using a commercial product made for what it is doing and installed properly was a cobble job. I really don't need a lecture for offering my experience and knowledge for free.

Now as to your question, why not give the size limitations, actual functionality based on theory of operation of what you need instead of screaming about something specific that is no longer made. I am not gonna do your homework and start looking up a bunch of stuff on Google when you can do that yourself. Especially for free information that, if you know what your doing, you can come up with yourself. Or call a radio dealership that handles commercial communications applications.

As to the purchasing, my county told me what they wanted, I gave them an estimate, and they accepted my bid. I do believe that is the normal channel for bidding and winning a contract. No cobbling there either.

I will follow you if I can truly be of help, but I won't do all the work to hand out free advice.
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73, Stan
Travelling the world one signal at a time.

KB8VUL

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RE: Mobile Radio Audio Combiner
« Reply #6 on: June 20, 2019, 07:06:20 PM »

Oh wait... . you are asking a commercial radio install question for YOUR commercial radio business on EHAM.  Then acting the fool when you get HAMMIE answers.
That makes perfect sense... No need to go to the USMSS web forum there Motorola dealers all hang out and answer these questions and send you a quote for the parts.

So, don't ask hams a commercial question and not expect to get a ham answer.
So the commercial radio question of what goes in the console.   Get them an NCS 250 box.  Will do what you are after with up to 4 radios and will patch the radios together as well.
It can be expanded to 8 radios if desired.
They are about 1500 bucks, plus the cable kits for the radios.
Havis and Troy both make face plates for them so you are covered there as well.

So in closing, if you are doing a commercial level install, state that in your original post. And if you are going to ask a bunch of hams that do everything on the cheap, expect a cheap answer or two. 
ANd go join the USMSS site.  All you need to be is a Motorola dealer to do so.  If your not, then you sell inferior radio equipment and should be ashamed of yourself and need to get with Motorola corperate and see about selling REAL radios and not some off brand copy cat stuff that wishes they were Motorola
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N2AYM

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RE: Mobile Radio Audio Combiner
« Reply #7 on: June 21, 2019, 06:32:40 AM »

When I built our county portable multi radio cabinet for field interfacing multiple channels, I did basically what VUL said except I did the mixing with a small PA mixer with a built in amplifier. It was a 1U 19" rack mount cabinet. I just built the radio speaker output cable for each radio with the voltage divider as part of the patch cable. Worked like a charm with very little effort or expense. Good audio quality and easy control. Plus being made by Shure, it was built like a tank. And if it ever died for some reason, it was a standard product which can be swapped out in minutes.

I did like having the control aspect as it was easy to mute any or all signals in my local speaker but yet not change anything going to the Harris interface controller.

You guys are not following me - whatever we buy has to be small like the Fleet Radio Products 4 port combiner so it can fit inside
either a havis or Troy console and not a bunch of parts that's cobbled together - local gov purchases and higher archy have some
requirements besides the common sense aspects of installing this inside a console.

Sorry...I didn't realize using a commercial product made for what it is doing and installed properly was a cobble job. I really don't need a lecture for offering my experience and knowledge for free.

Now as to your question, why not give the size limitations, actual functionality based on theory of operation of what you need instead of screaming about something specific that is no longer made. I am not gonna do your homework and start looking up a bunch of stuff on Google when you can do that yourself. Especially for free information that, if you know what your doing, you can come up with yourself. Or call a radio dealership that handles commercial communications applications.

As to the purchasing, my county told me what they wanted, I gave them an estimate, and they accepted my bid. I do believe that is the normal channel for bidding and winning a contract. No cobbling there either.

I will follow you if I can truly be of help, but I won't do all the work to hand out free advice.

I simply asked if anyone knew of a similar product to the
Fleet Radio Products audio combiner and then you went
off on the "tangent of the century" about a rack mount
installation when the title of this thread clearly states ""Mobile".
There is a good reason why i did that, that this need
is for installation in vehicles.
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N2AYM

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RE: Mobile Radio Audio Combiner
« Reply #8 on: June 21, 2019, 06:53:16 AM »

Oh wait... . you are asking a commercial radio install question for YOUR commercial radio business on EHAM.  Then acting the fool when you get HAMMIE answers.
That makes perfect sense... No need to go to the USMSS web forum there Motorola dealers all hang out and answer these questions and send you a quote for the parts.

So, don't ask hams a commercial question and not expect to get a ham answer.
So the commercial radio question of what goes in the console.   Get them an NCS 250 box.  Will do what you are after with up to 4 radios and will patch the radios together as well.
It can be expanded to 8 radios if desired.
They are about 1500 bucks, plus the cable kits for the radios.
Havis and Troy both make face plates for them so you are covered there as well.

So in closing, if you are doing a commercial level install, state that in your original post. And if you are going to ask a bunch of hams that do everything on the cheap, expect a cheap answer or two.  

ANd go join the USMSS site.  All you need to be is a Motorola dealer to do so.  If your not, then you sell inferior radio equipment and should be ashamed of yourself and need to get with Motorola corperate and see about selling REAL radios and not some off brand copy cat stuff that wishes they were Motorola


See my above response - same answer and your accusation above is way out of line! "YOUR commercial radio business".
I DO NOT have a business and simply work for local gov in support of various PD/FD/EMS and attempting to give
them quality installs in support of what they ask for. I did not know anything about "NCS 250 box" which is why
is asked in the first place. My internet searches never hit on that and after looking that over it is not what i am
looking for. The functionality needed is to combine up to 4 different radios audio into one speaker same as the
product I spoke of. The NCS device is a switching device and I need combining functionality up to 4 radios. It does
have some minor combining capability but that is not its primary function.
« Last Edit: June 21, 2019, 07:13:28 AM by N2AYM »
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W9IQ

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RE: Mobile Radio Audio Combiner
« Reply #9 on: June 21, 2019, 08:23:59 AM »

How many of these units do you need?

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

N2AYM

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  • Posts: 375
RE: Mobile Radio Audio Combiner
« Reply #10 on: June 21, 2019, 10:16:43 AM »

How many of these units do you need?

- Glenn W9IQ

Right now i have none. I was simply attempting to see what the market has to offer
and standardize on one model that would suit their and our needs. Apparently when
Fleet Radio Products went bust they left the market ripe for the taking of a nitch
mobile device. I usually acquire such devices and test one for a period to make
sure it works as it should and presents no problems.
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KD8IIC

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RE: Mobile Radio Audio Combiner
« Reply #11 on: September 27, 2019, 05:29:04 AM »

WHAT MAKES THESE WORK IS 600 OHM PRI 600 OHM SEC AUDIO TRANSFORMERS, ONE PER RADIO.
WIRE SPEAKER LEAD TO THE PRIMARY, SECONDARY SIDE TIES TO ALL THE OTHER SECONDARY SIDES OF THE REMAINING TRANSFORMERS, WIRE THAT UP TO THE SINGLE SPEAKER.
EASY HOMEBREW PROJECT FOR THOSE WHO WOULD WANNA MAKE ONE.
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W9IQ

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RE: Mobile Radio Audio Combiner
« Reply #12 on: September 27, 2019, 07:48:18 AM »

I have had problems with transformer only isolated speaker combiners. Some audio amplifiers don't like to be "back driven".

My preferred method is isolation transformer to attenuator to audio amplifier.

- Glenn W9IQ

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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.
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