Transmission1

One thing to be aware of with the baycom modems is they use power from the serial port to power the board. This can lead to a few issues, so If you are going to try a baycom modem using a TCM3105 which are getting rare now, I suggest you find a design that has an external power supply connection.

On the other hand, how about building your own TNC using an arduino nano?

http://www.m0pzt.com/blog/arduino-kiss-tnc/
Then you can use G8BPQ node software or TPK program or F6FBB BBS software.
or UIView for APRS tracking or AGW packet engine, or maybe Winpak?

Or run it on a Raspberry-pi maybe
http://www.prinmath.com/ham/howto/quickstart/

How about a TNC-pi or a TNC-x
http://tnc-x.com/TNCPi.htm
Lots of install and setup info available @
http://www.prinmath.com/ham/rPiHowto.htm

I fancy a play just for the hell of it.

the soundcard software by UZ7....is easy to try and alot more sensitive nowadays :-)

I have been experimenting with PSK31 (on a Stalker 9FDX) using fldigi running on a very modest laptop (using Linux). I am only using simple resistive attenuation for the audio in & out from rig to soundcard. For now, because of the problem of finding a simple relay, running off the pins of a serial port, I have been PTT'ing using a toggle switch!! It all seems to work.

Now, I don't want to get into too much complication and expence by building and using Rasberry Pi type stuff. I am however considering buying one of those "proper" (~£27) interfaces, as linked to further up here by Black_Pirate.

I write all this because I was wondering if someone could explain, in simple terms, what is the difference between some of the other "boxes" that have been mentioned, such as TNC, TNC-X and even the Baycom modem (that I used to own, so many years ago that I cannot remember what it did).
(I am guessing that they don't use the PC soundcard but are fed by digital information from a serial port, and they convert it into audio?)

"proper" £27 interface has galvanic isolation with transformers and optocoupler for PTT. It uses computer's sound card and CPU to do the modem stuff in software.
Baycom is a kiss TNC (keep it simple) that uses control signals in a serial port to bit-bang a modem chip to do the modulation and demodulation of bell202 afsk. Computer handles the data bit-by-bit.
TNC-X is based on a microcontroller and a modem IC and uses proper serial port communication with a computer. It is still a KISS TNC, so it cannot function without a computer like a real TNC can.

For curiosity, what radio do you use? If I can get a hold of the schematics of the radio I could probably come up with a PTT control circuit that fits your radio.

Cheers for the info ^^^

MikeSierra wrote:For curiosity, what radio do you use? If I can get a hold of the schematics of the radio I could probably come up with a PTT control circuit that fits your radio.

Stalker 9FDX, there is a good quality circuit diagram HERE

Thanks for the thought, but I'm thinking that all this isolation transformer stuff that you (and others) have mentioned must be quite important (for some reason ??) so perhaps, if I am going ahead with this, I should just buy one of these boxes (thanks to Black_Pirate for the heads up) as that, I think, has all I need and will PTT via the DTR / RTS serial port pins that fldigi uses. Am I right?

ghost123uk wrote:Cheers for the info ^^^
Stalker 9FDX, there is a good quality circuit diagram HERE

Thanks for the thought, but I'm thinking that all this isolation transformer stuff that you (and others) have mentioned must be quite important (for some reason ??) so perhaps, if I am going ahead with this, I should just buy one of these boxes (thanks to Black_Pirate for the heads up) as that, I think, has all I need and will PTT via the DTR / RTS serial port pins that fldigi uses. Am I right?

It seems you would need a PTT relay to replace the mike. Microphone audio probably gets cut out by the transistor close to C115, but RX control seems to do quite a bit in the radio. I cannot promise that PTT (TX) alone will do it.

It would be wise to contact M0AQC before buying his box, because the box will not necessarily work with your radio.

ghost123uk wrote: If only there was a simple (cheap) RS232 to DPDT relay board using the fldigi industry standard DTR / RTS pins for "Hi-low" switching

I have, (as mentioned above) tested my (simple resistive audio attenuated) system on air, via fldigi under Linux (on a laptop) and it works fine. I'm just stuck with manual PTT switching via that toggle switch

(from: http://www.g0hwc.com/sstv_interface.html )
I would also recommend to cut the microphone line when transmitting.
Start soldering

Is there still some activity regarding PSK31? Recently I finished my setup. Now I am trying to find out which channel and time gives the best chance of meeting someone. I am from the west coast of Holland btw.

I've had all my 11m PSK31 contacts on 27.500. Give that a whirl

Due to a big change of circumstances, I have not only not had chance to continue me experiments with this, I have not been on here for ages either.

Very soon both of those topics will be rectified

Looking forward to hear you're experiences. I received my transceiver interface yesterday. The final step is to tidy everything up and make the setup more mobile then the real testing can start.

Setup for now. Yaesu FT-817nd. XGGCOMMS interface to a Raspberry PI 3 running FLDIGI. Controls through keyboard and 10 inch touchscreen. It seems to work well for the limited testing I have done.

Yesterday I have been playing around with FLdigi. I turns out it has the ability to automatically report received PSK31 transmissions to https://www.pskreporter.info/pskmap.html. It even includes the 11 meter band. I am thinking about setting up a dedicated listening station to capture activity and find out what's happening and what the best times are to get on air. This makes it a bit easier to make futere contacts.

Besides 27.500 mhz what could be a good channel for monitoring?

Can anyone confirm they have managed to work any PSK /PACKET with a Uniden Boarded Radio say a Cobra 148 if so do you have the interface details thanks

Interface details: https://easyeda.com/Midas/interface-ded ... 6680a5948a

Anyone still using PSK31 out there? I had a beacon running last week but heard nothing