How I setup a 1986 TNC to send VHF packet email on a 1996 radio

[Smurf Hunter]

What you'll need:

1) a VHF mobile radio (while it's theoretically possible to do this with an HT, it's not recommended).

2) a TNC - I paid $20 for an old Kantronics KAM at a ham swap meet. An hour later a friend of a friend paid only $10 for his.

3) sacrificial ethernet cable (for this how-to we will assume the mobile radio uses an RJ-45 style mic jack)

4) DB9 male connector kit (you might consider hacking apart an old serial cable and splicing the raw wires as an alternative)

5) heat shrink tubing (for style and safety)

6) the only thing I recommend splurging on and buying new is the serial to USB interface.  This one is a known good chipset and is almost guaranteed to work perfectly.  You can spend a few $$$ less but dork around with driver software for an afternoon if you prefer.

http://www.amazon.com/GearMo%C2%AE-36inch-Windows-Certified-Drivers/dp/B004WM1WUY?
7) DB9 to DB25 adaptor.  This goes between the USB->serial cable and the TNC


For reference this is similar to what we'll be making:



Like any radio interface cable, the single most important thing is understand your radio's pin outs.  Every radio manual I've ever seen includes this.
Memorize this, write it down 10 times, or whatever it takes to not goof it up.  It's easy to do!!!

Step 1 - get the TNC connected to your PC
Plug in the USB to serial adapter into a USB port.  After the driver installs, goto Windows device manager and note the new COM port.
In my case it's COM14 (a virtual COM port if you are being precise).
This cable goes into the DB9 to DB25 adapter, and that plugs into the DB25 female port on the back of the Kantronics TNC.
So far any monkey with an amazon.com account should still be okay.

Step 2 - make sure the TNC is alive and your PC can talk to it
The easiest way to do this is using RMS express.  If you have that installed, in the base directory is an executable

Code: [Select]

RMS Simple Terminal.exeRun that, and specify the COM port from Step 1.  alternatively if you install the old MS windows HyperTerm.exe (for dialup modems) you can do similar.

Once you run your terminal program, connect to the TNC using the appropriate COM port and baud rate.  You may need to power cycle the TNC, but you should see output resembling this.



I'll post more soon...

[Smurf Hunter]

Now onto the interface cable.

You'll need to connect pins 1,3,5,6 form the TNC to the radio

Code: [Select]

TNC                        Radio
1 AFSK Out              Pin 6 (Mic Input)
3 PTT                      Pin 4 PTT
5 Audio Receive        *Connect this to the center conductor of a mini-mono plug and connect to the audio jack on the back of the radio
6 Ground**              Pin 7
**Tie this in to the ground on the mini plug as well
Pin 8 and 9 on the TNC are also grounds, so I connected those to the ground (shield) of the speaker line out. 
TNC 6 to Radio 7 and use TNC 8/9 to connect the ground to the mono plug.
In my case I used a stereo plug, that has 3 conductors like this:



Since my mobile radio speaker out is mono  (no left + right stereo signals) I shorted out the tip and ring to pin 5 on the DB9.
Also, I shorted out pins 8 and 9 on the DB9 together, and connected that to the shield of the phono plug.

Make sure you use a multimeter and use the Ohm meter to test out the pins on the RJ45 and write down which color wire they're connected to.

Here was my cheat sheet.  I personally find I understand things like this better if I write it down on paper.  It also was more convenient to take a piece of paper to my work bench.


Details about soldering best practices can be found else where, but I highly suggest you wrap each individual pin on the inside of the DB9 with heat shrink tubing after soldering.  Plan ahead, cut to length, but this will add some strength and durability.

Here's the final product.

[PrepperJim]

You got some skills dude.

[Smurf Hunter]

You got some skills dude.

Thanks, but I knew none of the is two years ago before I became a ham.

[Carl]

Thanks, but I knew none of the is two years ago before I became a ham.

Who ever elmered you did a great job...

[PrepperJim]

Thanks, but I knew none of the is two years ago before I became a ham.

Yeah, I look at one of the thread and thought to myself that Smurf has a two year head start. He asked many of the same questions I have so all I have to do is look at the How-To threads. If the question has been already asked, I just read through the thread.

[PrepperJim]

I will admit to the silly feeling of being slightly intimidated by building a simple 10m dipole. Goodness gracious, I am a flipping engineer of another sort (not that being an engineer grants me special powers mental or otherwise), assembled all sorts of things (my specialty is baby furniture and toys), handle highly technical chemicals all day, etc etc. And yet and making two solders, cutting and measuring two wires, bending them around insulators gets me thinking I can just buy a 10m antenna from R&L and rock on. But what fun would that be?

Of course, this is the same guy who has not routed coax to his attic yet and considers a cookie sheet on top of his office bookshelf to be an accomplishment. ;-) (That is, until I could not transmit or receive from a repeater 25 miles to the north east)

Time to place that coax, connector and balun order with R&L.

[Carl]

I will admit to the silly feeling of being slightly intimidated by building a simple 10m dipole. Goodness gracious, I am a flipping engineer of another sort (not that being an engineer grants me special powers mental or otherwise), assembled all sorts of things (my specialty is baby furniture and toys), handle highly technical chemicals all day, etc etc. And yet and making two solders, cutting and measuring two wires, bending them around insulators gets me thinking I can just buy a 10m antenna from R&L and rock on. But what fun would that be?

Of course, this is the same guy who has not routed coax to his attic yet and considers a cookie sheet on top of his office bookshelf to be an accomplishment. ;-) (That is, until I could not transmit or receive from a repeater 25 miles to the north east)

Time to place that coax, connector and balun order with R&L.

We will; help you as needed...proceed with confidence.

As far as reaching a repeater ,LINE OF SIGHT....you reach a repeater because of the repeater ,and you ,antenna height above ground  and the added factor of PATH LOSS due to atmospheric inconsistencies...though I did talk to a 4 watt HT in and aircraft (5000 feet) up and over 90 miles away. Building or terrain about YOU effect your signal more than power...50 watts would help ,but not nearly as much as you think...

The first astronauts on the moon were heard direct from their suit radios...ONE WATT VHF radios ,designed by a Ham ...heard across the vastness of space....unless you live on a mountain this is of little value.

DOUBLING of POWER 5 to 10 watts ,equals 3 DB ,the minimum discernable change in power...I have found most repeaters require 6 DB increase to allow for improved signal or from 5 to 20 watts and the jump to 50 watts ...only a tiny bit better...BUT a ten foot change in antenna height can make MORE than the extra power!!

So ,don't get carried away with power...height above terrain and a clear path are your primary considerations for VHF/UHF ,not power.
I have a small VHF station with a single beam at 35 feet,I regularly speak with others to 400 miles away with SSB (single side band)
VHF though this does not represent repeaters as they are not generally accepted as more than LOCAL communications devices.

Line of sight says a 200 foot repeater antenna is effective to about 27 free air miles...all repeaters are NOT EQUAL,though typical is 50 watts at the repeater and 20 or so watts making the antenna...THEY command the frequency due to height above ground...NOT power output.

Well sorry I wandered about , but understand ...it is exceptional that you can reach a repeater 25 miles away ...but it has little to do with your radio or radio power...on VHF...the antenna and antenna position are all important.

[PrepperJim]

As far as reaching a repeater ,LINE OF SIGHT....you reach a repeater because of the repeater ,and you ,antenna height above ground  and the added factor of PATH LOSS due to atmospheric inconsistencies...though I did talk to a 4 watt HT in and aircraft (5000 feet) up and over 90 miles away. Building or terrain about YOU effect your signal more than power...50 watts would help ,but not nearly as much as you think...

Yeah. I suspect it is a line of sight issue plus I am a good distance from the repeater. Getting the antenna higher will improve the chances although it might not be tall enough in the attic. We will see tomorrow.

I had a hard time finding some local coax with connectors. I ended up buying 100 ft of RG58 with BNC connectors. It took a 2nd trip to get the right connector for the PL239 on the antenna. If 100 ft degrades the signal too much, I can always cut it down and put a connector on it. I just wanted to get some coax up this weekend as the radio is going to arrive either Monday or Tuesday.  I think it will be OK as I am hitting the close repeater with my HT through the cable.

[Carl]

Yeah. I suspect it is a line of sight issue plus I am a good distance from the repeater. Getting the antenna higher will improve the chances although it might not be tall enough in the attic. We will see tomorrow.

I had a hard time finding some local coax with connectors. I ended up buying 100 ft of RG58 with BNC connectors. It took a 2nd trip to get the right connector for the PL239 on the antenna. If 100 ft degrades the signal too much, I can always cut it down and put a connector on it. I just wanted to get some coax up this weekend as the radio is going to arrive either Monday or Tuesday.  I think it will be OK as I am hitting the close repeater with my HT through the cable.

At VHF frequencies ,you ONLY lose about 75% of your power per 100 feet ...I would look into other (RG8X/Mini 8 coax) AND shorten the length.

coax loss chartt
http://www.w4rp.com/ref/coax.html

Good place I get coax from..great rep for most any who use them...I use the JETSTREAM mini8 ,in bulk or pre-made

http://www.randl.com/shop/catalog/index.php?cPath=11030

Popcorn time   

[PrepperJim]

At VHF frequencies ,you ONLY lose about 75% of your power per 100 feet ...I would look into other (RG8X/Mini 8 coax) AND shorten the length.

coax loss chartt
http://www.w4rp.com/ref/coax.html

Good place I get coax from..great rep for most any who use them...I use the JETSTREAM mini8 ,in bulk or pre-made

http://www.randl.com/shop/catalog/index.php?cPath=11030

Popcorn time   

Yeah. I am standing there in the local Fry's, the wife and the boy staring at me, and the with only option of 100 ft of cable with BNC  connections, no other options, no crimp or solder connectors available, and thinking to myself, "what would Carl do?" Since I cannot fathom what Carl would do because I have my ticket for <1 month, I decided to just try something. If it did not work, I would be out $28 bucks, some time and have learned what did not work. As it is, I hooked up my Baofeng HT, 100 ft of RG58 plus the PL259 connectors to BNC (X2), with my cookie sheet, Tram 5/8 wave on top of the book shelf and the #2 local clique dude gave me a decent signal report and then the #1 clique dude did the same.

Tomorrow, I will attempt to cut a bigger hole in the closet ceiling, route my coax to the attic, put the cookie sheet up there with the Tram 1185 and see what is what. I suspect that the antenna will become the limiting factor.

Frankly, my biggest problem right now is the external microphones. I have two of them and am about ready to throw them in the trash. I had to disconnect and talk through the HT PTT. If only I could get a decent external microphone with a 3.5 mm jack for the Baofeng.

[Carl]

At least you got some popcorn....
The RG 58 will do OK and you will recognize the value later when you get better coax...
The RG 58 will work better as HF or scanner antenna connect.

My coax (Mini 8,RG8X) has been in use for over 20 years in high moisture exposed to sun nature and has yet to show degradation...I think of feedline as an investment in effectiveness and antennas too are more important than what radio you use...kinda' backward as Joe Ham looks for the biggest ,chrome plated,button encrusted,massive display radio he can find...there are $20K radios now....WHY?

[Smurf Hunter]

Minor update regarding the FTDI USB to serial adapter.

Apparently for the RS232 (serial) port to function, a certain amount of current is necessary.  This matters in case you plan to plug in the USB end into a USB hub.

A USB hub that is not powered won't work. (meaning no dedicated wallwart or other power beyond the PC USB port where the hub goes).

Your mileage could vary, but if any folks are reading this later, I wanted to suggest setting up without a USB hub in case you're having problem.s