Sunday, August 8, 2010

Digital Flashback

Lately I was digging a bit in my goodies boxes... and some treasures surfaced in the for of digi-mode controllers.

Next to two TNC2s, a Kantronics KAM (w/ Pactor I), an SCS PTCplus, an AEA PK-900 and an SCS PTC-IIe found their way out of the dark.

Hmmm, this has been my active Packet-Radio and Pactor period. Now:
  • What happened to the controllers?
  • Are still in a working order?
  • Would they be able to communicate with modern computers?
  • Is there still software available, for these controller, which runs on modern computers?
  • Is there still activity?
  • What could the stuff be used for?
Questions questions....

I tested all controllers but the PK-900, which simply is too clunky for the tiny test space I freed.
The tests concerned the compatibility of modern computer hardware with those old controller, hence no radios connected, no RF generated.
So, here's some of the results and thoughts.

All tested controllers still worked.

For testing, I used three relatively new computers in the setup, running different operating systems: an Acer REVO w/ Windows Vista, an Acer Aspire One running jolicloud 1.0 and an MSI Wind under Windows XP. None of these computers have RS232-ports, which in modern times seems the first hurdle.
In a recent order, I purchased a cheap no-name USB-to-serial adapter (Prolific PL2303 chipset), which plugged into the SCS PTCs directly. For the other controllers, a "9to25"-adapter was required.
BTW, Vista provided me with the most struggle, a lot of blue screens, core dumps and what not...
jolicloud was the only real plug&play what the PL2303 is concerned, and smoothly installed the device as /dev/ttyUSB0.

Struggles aside, let's have a look at the results.


Packet-Radio

Software: PAXON under Windows Vista
TNC2 (TF2.6, modified to 10MHz Z80, 38400bps): doing just fine!
Symek TNC2S (TF2.7): something caused the TNC to stall in TX (remember, no radio connected!), with my hand placed on the controller, this did not occur. Seems there is some grounding problem between the PC, the USB-device, the TNC and the TNC's (linear) PSU.





AMTOR & Pactor

Windows software: Airmail3 for hams, Alpha 3.2, Simple32

Airmail3 seems to be the reference, it could talk to all modems, on either Windows flavors, although, it has been a struggle to have it talking to the KAM under Vista, no problem with XP though. Airmail3, as the name suggests, is an HF email program, which makes use of the WINLINK2000 Global Radio Email System. Airmail3 is therefore mainly programmed for handshaking with the servers of said system and therefore is essentially limited to Pactor.

Alpha 3.2 did only talk to the SCS PTCs, however, it did it well.

Simple32 simply did not work on Vista, whatever I tried (run it under admin, etc.). I got the main screen just once after hitting ignore on all error-messages, and, it did not at all look simple, hence I decided to not (yet) give it a try on XP.

Linux software: Kptc, minicom

Kptc flawlessly installed on my jolicloud 1.0 netbook. The program works perfectly with the SCS PTCs.

minicom seems the only easy way to communicate to the KAM. A software called Kamplus was written some years ago. I will try to compile it on my machine, I will post any success story; I will however spare you stories about failed software porting efforts.


Conclusions

Packet-Radio seems a dying mode, at least here in my region. When I moved here, I was eager to keep contact with my friends via the PR-network, I soon learned, that this region is not connected to anything. I wonder I that changed. Maybe APRS would be an option.

AMTOR was a very advanced technique, to the time when I got on the air for the first time. Those chirps were everywhere.... I have not heard many on the ham-bands lately. However, there seems to be one BBS station in Germany, DA5TOR, still on-air. I should give it a try, once my NVIS antenna is set up.

Pactor = eMail nowadays... DXers are busy using narrowband modes like PSK31. Pactor, when I did it last, could provide an even better robustness, but, for what price? Modern PTCs are more expensive than decent HF transceivers! No wonder that the mode more and more drifted towards professional application, e.g. marine communications such as SailMail.


Next Steps

Yes, I will take next steps. Among my transceivers, I will find the ones that make the least noise and provide the fastest switching.
A good start in this respect could be the Ten Tec Scout, if the frequency stability proves to be sufficient. I used this transceiver with PSK31 and Pactor I before, back in the days. The Scout is, besides the strange noise created by the PTO, totally silent, no relays involved... could be perfect.
Then there would be the Kenwood TS-140, which I used for WSPR for some weeks a year ago. The TS-140 has got relays, and is therefore somewhat unpleasant when used with ARQ.
Technically, the best fit would be the ICOM IC-M710. Not only was it built for the purpose, remember TOR (Teleprinting Over Radio) is a marine application, Airmail3 can actually control the radio via the NMEA bus. The IC-M710 also provides a frequency stability superior to most ham-radios. The radio however employs a lot of mechanical switching.
Last but not least, the following approach could be considered (this will be a new blog entry, when taken seriously): Use a DDS, controlled by a PIC, PICAXE or Atmel, as a LO for something that either already transceives silently, e.g. an old Scout, SmallWonderLabs PSK-series, N3ZI's 612-PCBs (see earlier blog entry) or this.

Sunday, August 1, 2010

Grabber up

The grabber is back online for some hours now. No adverse effects yet. Let's hope it stays that way.
There is one minor change, the grabber is now using my G5RV-jr and not the DCTL.

Thursday, July 15, 2010

30m QRSS/WSPR crystal combi

Short notice about a combination a accidentally saw:
  • 18.138 - 8.000 = 10.138
The beauty here, it is subtractive, thus, thermal effects should (nearly) cancel out.
The 18.138 crystal is made available by VK1AA.

In terms of design, this [click] looks like an interesting approach. Although, I consider the use of 74HC4066s.
Thinking of a design, a 4MHz subharmonic l.o. comes to my mind, after all, subharmonic mixers are also bi-directional.

Monday, July 5, 2010

good ole times

I loved my stay in Hamburg.... I have been visitor to the "Hamburger Staatsoper" every two weeks.
In that course I also enjoyed this performance: http://www.youtube.com/watch?v=ZoCrwzUi3aM
This was from the second act "Suor Angelica" of the opera "Il Trittico" by J. Puccini.
To keep my promise to Jan, here're some highlights of the other parts:
First act "Il Tabarro": http://www.youtube.com/watch?v=fAQziZWs9xo
Third act "Gianni Schicci": http://www.youtube.com/watch?v=w0diDwHtATw

Could be some idea to open up a blog on opera :-)

Wednesday, June 30, 2010

QRT for a while (please help!)

At the location of the Suburban Subharmonic Grabber, generation of electro-magnetic fields is ceased temporarily. This includes the local oscillator of the subharmonic direct conversion grabber receiver(!). BTW: WLAN is shut down too, for the time being.
I hope that I will be able to provide grabber-services again, sometime.
It seems that, nowadays, spectrum grabbing is a suspicious activity!!! Oh, and... it seems that even writing about ham-radio is dangerous!!!
In order to support my "case", please feel free to write some comments to this post.
With your help, people may understand that what we are doing is just a matter of fun and helps studying propagation phenomena.

Wednesday, June 9, 2010

The Modern World

One step is made into a more modern world of amateur radio... I nailed together N3ZI's DDS-2 kit. Really easy to build! Did some playing with it, but no calibration yet.

Monday, May 31, 2010

MEPT Idea

One my search for detailed information about the Sangean ATS-909 (aka Radio-Shack DX-398, Siemens RK777 and Roberts R861), I was able to locate schematic diagrams.

The reader may ask what that's got to do with a MEPT... well, nothing up to now... BUT:

 When checking the receiver's control PCB schematics, I found something, the main micro-processor generates the PLL reference signal. Maybe it is always done like that, I don't know, but it looks remarkably simple to me.

In the upper right corner, that would be the micro-processor. The chips leads X1 and X2 are connected to a 4.332MHz crystal. This oscillator is the classical Pierce configuration, as we know it from so many digital applications.
The crystal's cold end is provided with a trimmer (TC301) for frequency tuning.
The crystal's hot end is connected to an RC low-pass filter (R389,C363) which further feeds the signal into the PLL chip.
BTW: Can someone explain the function of C359 to me? It seems to couple GND to GND.... hmmmmm(!)

So, here's the MEPT idea (actually, this was done before, sort of, by Clayton from Down Under): clock the keyer (e.g. 12F629) by its high speed built-in oscillator, using a crystal for a QRSS frequency and couple the signal out in the way the professionals do :-))
There is just one down-side to this, the controller's clock is now at a somewhat odd frequency, odd for controllers that is, so timing could be off. I will check if compilers (I am programming in C, not in assembler) are able to compensate for that...

Now that we got the signal, what shall we do with it? Well... amplify?!
For another project, I happen to study switch-mode amplifier, aka class E or F. F seems a little bit too much work, but E seems fine for a MEPT, as Hans proved with his Caribbean beacon. Hence, a class E amplifier seems appropriate; I guess, the crystal's hot end will have enough voltage to switch a FET.

The chip could serve for than just the oscillator and the keying device.
During my time at various physics experiments I experienced the difference between fast control and slow control. In our experiment slow control was taking care of temperatures...
So, with seeing the keying as "fast" control (well, sort of fast), controlling the crystals temperature could be integrated as slow control. Those PICs got ADCs, which could easily be used for measuring temperature.

My present vision for mini-MEPTs is presently:
  • one PIC clocked by a QRSS-xtal
  • one FET as PA
  • oven control by the PIC
  • telemetry?

The whole story could have some other advantage.... I realized that, depending on the TX frequency, some PICs stall when RF leaks in. If the controller is clocked with the same frequency and phase, this should not occur.

Next step: design something! Stay tuned, I will let you now as soon as I got more. For now you may click on one of the "sponsors" to find your way out of this blabla...

Sunday, May 30, 2010

ATS 909 Idea

What about using the ATS 909's frequency generation for transmitting?
As soon as time allows, I will have a look into the service manual to find out more.
Meanwhile, here's the source for the manual:
http://www.ab9il.net/ats-909/ats909-manuals.html

Full Duplex QRSS TRX Idea

This has been in my head for some time... What about in-band full duplex QRSSing?
Some preconditions we have to look at. For a successful slow QSO, we need to assume condx of a single band, so that both stations can receive the counterpart equally. TX during RX in one band at the same time is a challenge even on the 2m-band. So, what can be done?

The problems, I figure, are more on the receiving side of the design. So here are some preliminary ideas that came to my mind:
  • frequencies in one band, the furthest possible apart
  • a very narrow-band RX antenna, e.g. a high Q magnetic loop
  • a crystal notch filter for the TX frequency
  • a crystal front end filter
I have no idea if this would actually work...
However, for experimentation, there are a couple of possible frequencies (cheap crystals available).
  • 80m: 3.500MHz & 3.6864MHz
  • 40m: 7.000MHz & 7.15909MHz
  • 20m: 14.000MHz & 14.31818MHz
  • 10m: 28.188MHz & 28.636MHz
The high crystals for 40m and 10m may be a little difficult to find, check DigiKey. All others are either standard, or available at GenesisRadio. Remember, we need a crystal for every QRG, at least for the notch filter!

For me, the obvious choice for making a full duplex QRSS transceiver would be K1SWL's 80m-Warbler. I could show that the Warbler is quite potent on 40m when modified. I would assume that the kit could equally modified for the 20m band.
Based on the Warblers, one would need two per band. The Warblers make nice transmitters too...

Another approach could be the use of a superhet receiver with a (switchable) notch filter in the front-end, remember, it is all about keeping the TX out of the RX when going full duplex.

Monday, May 17, 2010

IC-M700D LSB update

Wow, how cool is that. This morning, the postman dropped me a padded letter through my door. The letter contained a 4922kHz crystal! Unfortunately, no sender was noted. Must be a reader of this blog though ;-)

Dus, grote dank aan de OM achter de brief! Idd, de kristal is iets groter dan het origineel. In de doos van de IC-M700 zelf is gelukkig zooooo veel ruimte, dat dit helemaal niets uit maakt.
Ik zou me ook graag personelijk willen bedanken, maar, ik weet hellaas niet bij wie...

I hope, that this crystal can be pulled downwards enough, 2kHz should not be a big deal, so that grinding would not be required. I will, additionally, invest some time in finding out how to grind up modern crystals, so that more owners of non-LSB IC-M700 transceivers will be able to modify their's.