[arm-allstar] Baofeng COS without opening the radio

[Doug Crompton]

Rick,

  I am told from a reliable source that if you use US mail first class mail
NOT priority, Not UPS or FEDEX  the shipping to AU is quite reasonable.


*73 Doug*

*WA3DSP*

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


On Sat, Mar 2, 2019 at 11:28 PM "Richard Perks via ARM-allstar" <
arm-allstar at hamvoip.org> wrote:

> Thanks for posting this up Steve - Looks very interesting as I'm looking to
> reduce the cost of building a node. The DMK URiX RIM works well but with
> the high cost of shipping from the US to Australia it's very expensive.
> I've ordered up some different types with cheaper shipping but wanted to
> try the super cheap to compare. My problem is I don't know the first thing
> about how to etch. Any chance you could point me in the right direction
> please ?
>
> 73
> Rick
> VK4HC
>
> On Sun, 3 Mar 2019, 11:55 "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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> >
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