Some success with the TNC-Pi

[Brian Lawler]

My saga continues....

The SLOW boat from China finally arrived with my radio cables.  I have confirmed that my modem chip is in good shape- I can send and receive readable 1200 baud packet (HOORAY!).  So- putting the modem chip in backwards did not kill it :D

The last hurdle is PTT.  I see the TX LED light and the data is flowing, but it won't key the radio.  I am connecting to a Baofeng HT (UV5R).  If I short the radio PTT line to ground, it keys.  The Baofeng diagram that I found labels one wire as Mic - / PTT and the other as SPKR - / PTT so I tried both connections to TNC GND and PTT. I did a bunch off Googling but found no one else seems to have this issue (of course).

BTW I will miss the Digi meeting on the 21st so hopefully someone can bring a working packet station to the library help folks test their units.

[Art Miller]

There is probably a resistor and cap to do the ptt... most radios do it...

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[Robert Sears]

Indeed my Yeasu needed a cap and a 2k resistor.

I believe there were two 'lines' a speaker(Rx Audio) and Mic/PTT

The cap separated the Mic from the DC offset. So the cap went from the radio Mic/PTT line to the Tx audio on the TNC

The resistor went from the radio side of the capacitor to PTT on the TNC

The speaker of course goes to the Rx audio on the TNC

Robert/KF7VOP

[KNØN]

Oh, Occam's Razor, you nicked me again.

So my FINAL round of troubleshooting had me tracing the connections from the radio back to the TNC-Pi.  Rather than just trace ground to the plug, I traced to the board- NO contact.  It turned out that when I went to solder the ground to pin 6, I glanced at an upside-down connector and soldered it to pin "9" <<forehead slap>> .  The TNC-Pi is finally working as advertised.  I used my radio cable with a Signalink and it worked fine, so I knew there had to be an issue on the TNC-Pi end.  Kudos to Coastal Chipworks for designing their kit to withstand knucklehead builders.

In order to make the TNC-Pi inter-operable with my other rigs, I made the D-9 cable with a male 6 pin mini-DIN, conforming to the jacks on the back of most V/U rigs.  I then made my Baofeng cable with a female 6 pin DIN, also conforming to the standard.  The Baofeng now works with wither a Signalink or the TNC-Pi with no cap or resistor required (you do need those for some HTs however).  One more caveat that I read about, and experienced-  When you are using an HT near the boards, RF can get into the TNC and hang the TX, so keep that in mind if your rig tends to stay keyed too long.

-Brian

[Robert Sears]

Speaking of RF noise the Pi it's self is known to be noisy and has no shielding nor does a plastic case add any.

That's yet another reason you gotta keep 'em separated.

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[Art Miller]

You can buy the metal shielding material and build your own case (laser print of course) then line the outside with the shielding :)

[Budd Churchward]

Jumping in here late.

I have the same HT and have it working. I used the cable I bought for a SignaLink. It has an RJ-45 on the end of it so I soldered a jack onto a piece of perf board and routed the four center pins of the jack to a header that I run over to the 'Radio' pins on the TNCpi. It seems to be working, I can hear my own packets but I am having big issues with the TX delay. No matter where I put R6 the PTT stays on for 20-30 seconds. The little rubber ducky antenna connector gets might hot! Perhaps the TNC isn't turning it off at all. Maybe the radio is timing out itself ???

I need to do some more research.

On Saturday, April 4, 2015 at 9:25:28 PM UTC-7, KNØN wrote:

[Art Miller KC7SDA]

You have to set the TX delay in the firmware OR you have to set the firmware to use R6.

[Gayland Gump]

Anyone wire up a cable for a TNC-Pi/Baofeng UV5R yet? Does it require a cap and or resistor?  Really not quite with it on the hardware end of things?  Software is a bit more in line with my experience.  Robert, If you are still willing I'd welcome the opportunity to take you up on your previous offer of help.  I'd like to get a couple of cables made soon.

Gayland

KG7GCF

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[Art]

Here is the pinout:

DB9:               Connector:
1 (tx audio)    3.5mm ring
3 (ptt)             3.5mm sleeve
5 (rx audio)    2.5mm tip
6 (ground)     2.5mm sleeve

There are a few images (fairly poor quality) that show how to hook up a UV5R... so far I've not seen any schematics that show caps and resistors.... wish more radios would do this... lolz!

[Brian Lawler]

On Tue, Apr 28, 2015 at 9:21 PM, Budd Churchward <barnac...@gmail.com> wrote:

Jumping in here late.

I have the same HT and have it working. I used the cable I bought for a SignaLink. It has an RJ-45 on the end of it so I soldered a jack onto a piece of perf board and routed the four center pins of the jack to a header that I run over to the 'Radio' pins on the TNCpi. It seems to be working, I can hear my own packets but I am having big issues with the TX delay. No matter where I put R6 the PTT stays on for 20-30 seconds. The little rubber ducky antenna connector gets might hot! Perhaps the TNC isn't turning it off at all. Maybe the radio is timing out itself ???

I need to do some more research.

Budd-  That sounds like you might be having some RF getting in to the TNC.  I read about that happening when I was troubleshooting mine.  Make sure you have some separation between the radio and the TNC/Pi.

-Brian

[Budd Churchward]

WARNING! This image shows you which leads do what on the radio plug. Pins 2 and 4 on the DIN connector are wrong for out project. See Art's notes for that end. I didn't use the DIN connector. I am hooking mine up to the four pin header labeled: 'Radio' on the board. NC, of course, means 'no connection'.

[Art]

Also, I have a bunch of the female plugs to go onto those headers, they come in several colors to choose from, since both ends are female I'll just cut the wire in half and save the other end for another set of connectors =)

[Robert Sears]

Sure I can help you get it all soldered together. I have the week off so anytime in the next few days is good for me

Robert/KF7VOP