[arm-allstar] Baofeng COS without opening the radio

[wb4bxo at mindspring.com]

Certainly Doug, that's why I put it out there. Hope it helps. I'm also still 
looking at having some boards for just the interface made, if enough people 
are interested for me to order 100 I can get them for a little under $4 my 
cost bare board with masks and silkscreen. I tweaked the layout a bit today 
and hand made another board with the layout mirrored from the original so 
that the interface mounts over the top of the sound FOB. I'll put info and 
pictures up in the same folder here in a few minutes, look in the directory 
with "Flip" in the name. It makes for a much smaller package.

I'll also put up the laser printer files that can be used to heat transfer 
and make your own boards but it may be tomorrow before I get those up.

73's
Steve - WB4BXO

-----Original Message----- 
From: "Doug Crompton via ARM-allstar"
Sent: Sunday, March 03, 2019 2:39 AM
To: ARM Allstar
Cc: Doug Crompton
Subject: Re: [arm-allstar] Baofeng COS without opening the radio

Steve,

If this is reliable it looks like a good way to do it. If it is OK with
you I will add the info to the Baofeng  howto mods.  We also could easily
produce a board in quantity to do this if there was a demand. I find any
more that most do not want to turn on (or have) a soldering iron so any
amount of mods are out of the question. We are currently sourcing two
models of FOB's, the ARA1 and the ARA1+. Since the yellow box nodes use
Baofeng radios and are sold in large quantities it might be advantageous to
build a FOB specifically for those radios using this method. If we test it
and it works and we decide it could be a product do you have any objection
to our use of your circuit?


*73 Doug*

*WA3DSP*

*http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*


On Sat, Mar 2, 2019 at 8:55 PM "Steve via ARM-allstar" <
arm-allstar at hamvoip.org> wrote:

> I have put together a little circuit that allows connection to a Baofeng
> UV-5R HT providing COS without having to open and modify the radio itself.
> This works great for AllStar, packet, APRS, or most anything that requires
> a soundcard connection to the radio complete with COS. I have even used
> this circuit without the sound card to connect to an RC-210 repeater
> controller.
>
> I built the circuit based on the schematic of the UV-5R but I believe most
> of the Chinese radios will work with it. I have tried it on several
> different Chinese radios including the Anytone AT-D868UV DMR radio and 
> they
> all worked fine. However, even though these radios are mimicking the
> Kenwood two prong speaker/mic connector, this circuit will not work on my
> Kenwood TH-F6. This is due to the fact that the Chinese radios do not 
> block
> the DC of the audio amp from reaching the headset, which is why you hear a
> pop when the squelch opens and closes on these radios, and is what this
> circuit counts on to turn on Q1 and provide COS. The Kenwood doesn’t work
> (or have the pop) because it has a blocking capacitor and an MOS switch in
> the audio line that prevents the DC from coming out the jack. But I’m much
> happier using a $35 radio for this purpose anyway.
>
> I’ve hand etched a couple of boards for it so far and may send it to a
> board house to make some prettier boards, especially if others are
> interested in it (I’ve already quoted them and its just too pricey for
> small quantities, which is why I decided to hand make the few I needed).
> The boards I have made have some extra pads on the end to allow soldering
> directly to the audio jacks of one of the EBay sound FOBs, just makes it a
> bit cleaner than having to cable that side of it, though it still requires
> the two jumpers to the GPIO lines on the sound chip. Also note that there
> is an extra connection at Pin 4 on the sound card side that should allow
> using with an RA-35 or similar that already has the open collector driver
> for PTT. I have not tried this on an RA-35 but feel confident it would
> work, my target was primarily the CM108 open board sound FOB you can get 
> on
> EBay and Amazon.
>
> https://www.ebay.com/itm/CM108-USB-Drive-Free-Sound-Card-Laptop-Computer-External-Sound-Card-Module-New/263928310585?hash=item3d735a6b39:g:SSwAAOSwEVlcDcAU:rk:1:pf:0
>
> Also note there is no activity detection nor time out timer in this
> circuit, so I leave the TOT of the attached radio set to something
> appropriate in case things get hung up in transmit. And as with other
> interfaces, make sure to keep the RF from the attached HT from getting 
> back
> into the RPi.
>
> Schematics, some pictures, and this doc can be found here, hope it helps
> someone.
> https://www.dropbox.com/sh/lrv9uwkgx8tpm6y/AAD2syTNpZDwcjX1gA8zjV9Va?dl=0
>
> Steve – WB4BXO
> http://www.stevemobley.com
> _______________________________________________
>
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