AmateurRadio.com

At around 9PM on May 31, 1978 were the first KNOWN transmissions of Packet over Amateur Radio. The location was Bill Wong’s Restaurant in Montreal, Canada.

The Montreal Packet Net Group C/O:

Bob Rouleau VE2PY; Norm Pearl VE2BQS; Fred Basserman VE2BQF; Bram Frank VE2BFH; Jacques Orsali VE2EP; Ted Baleshta VE3CAF; Ian Hodgson VE2BEN; among others not mentioned.

They operated on a single 220Mhz channel using start-stop ASCII with the Ethernet CSMA/CD protocol. The protocol was modified for amateur applications by Robert T. Rouleau, VE2PY, and implemented by Fred Basserman, VE2BQF. Montreal Packet Net (MP-Net) Operated at 2400 bit/s using home-built modems.

A detailed description of the Montreal Protocol and hardware used in the experiments is given in the TAB book #1345 “PACKET RADIO” by Bob Rouleau and Ian Hodgson published in 1981. An interesting note is that the Montreal Modem design used the Exar XR-2206/2211 chip set. I am told that a sample of the Montreal Modem was sent to the Vancouver group (VADCG) in the fall of 1978 and it is probably no coincidence that the same chip set appeared in the TAPR TNC modem of which Doug Lockhart of VADCG had a hand in designing.

After an initial spurt of activity in amateur packet, Bob Rouleau and several others in the group turned to commercial applications for packet radio. The resulting company, DATARADIO Inc, today is building and marketing commercial packet radio systems around the world. A typical application is the Canadian Weather Radio packet service introduced some years ago using DATARADIO equipment specially designed for the application.

Bob was inducted in the CQ Magazine Amateur Radio Hall of Fame in 2003.

Jack, W4JBR, is a special contributor to AmateurRadio.com and writes from Georgia, USA.

As I wrote in my blog post a few days ago, I got the intensity down for night vision for my red flashlight. But I wasn’t quite happy with the level and wanted to reduce it even more. To do that I had to unsolder 6 of the 8 AMC7135 350 mA constant current ICs on the PCB of the AMC7135*8 2800mA 4-Group 5-Mode Circuit Board.

These constant current chips are all run in parallel with the VDD input for control. The 8-pin Atmel ATtiny13A chip controls all VDD inputs in parallel from its pin 6. When the VDD pin is low there will be now light. I haven’t measured this, but I am assuming that this pin is pulsed in order to reduce current down from the maximum.

My measurements for the High, Medium, and Low settings are:

• 8 chips: 2,8 A, 0.83 A, 0.14 A
• 4 chips: 1,4A, 0.45 A, 0.08 A 
• 2 chips: 700 mA, 225 mA, 42 mA

This scales as expected with the number of 350 mA chips and the 100%, 30%, and 5% settings of the controller. Now only Q1 and Q3 remain, and Q2, Q4-8 have been desoldered.

One could have obtained en even more battery-friendly version if somehow the original controller could have been modified. The step-down circuit is quite standard with an inductor, a Shottky diode (SS14), and a controller chip of unknown origin. But it seems to me that if R23 of value R250 (0.25 ohm) was increased, output current would probably go down.

As it is I am much more happy with the intensity of the settings I have now. It will be a good companion night light which will preserve night vision well when used with a telescope.

Sverre Holm, LA3ZA, is a regular contributor to AmateurRadio.com and writes from Norway. Contact him at [email protected].

Michael Brown, KG9DW, is a regular contributor to AmateurRadio.com and writes from Illinois, USA. Contact him at [email protected].

See http://www.southgatearc.org/news/2015/february/ht_of_the_future_at_orlando.htm#.VNi6BC4WKPc .

Southgate News reports that Bruce Perens K6BP will be demonstrating a handheld platform that can cope with many modes at VHF/UHF at the Orlando Hamcation in Florida. This looks like a demonstrator at 100mW RF. With SDRs, quite a flexible, and low cost, architecture is possible.

I wonder which of the “big names” will be first to market with a real SDR design? This could enable them to sell very low cost units, but maybe they would rather shaft us and make big profits?

Roger Lapthorn, G3XBM, is a regular contributor to AmateurRadio.com and writes from Cambridge, England.

As I have mentioned before, I am a rare repeater user, partly because my voice is so poor currently and I don’t find operating through repeaters that satisfying. Each to his/her own and if this helps you enjoy the hobby go ahead!

At the moment it is far from clear which form of digital repeater will win: there are several competing digital standards and all have their advocates. For now I shall sit back and wait. A bit like the video standards war in the 1980s, the best system may not win. Let’s see. Up to now I have only used FM repeaters.

When I do use voice I use SSB, FM and AM. All modes have their places on our bands. SSB is good on the crowded HF bands, FM useful for nets on VHF, and AM rigs simple to build and there is space on all bands from 10m upwards for all analogue voice modes. A well designed AM rig should occupy less than 6kHz, far less most FM transmissions on our bands. 10m AM, just above 29MHz, is a great mode. I have worked quite a few stateside stations on 10m AM. And I have only used QRP AM.  Let no-one tell you AM is a dead mode!

Roger Lapthorn, G3XBM, is a regular contributor to AmateurRadio.com and writes from Cambridge, England.

630m to HF Crossband

Since getting the new 630m band (472-479KHz) here in Canada, one of my favorite ways of promoting interest in the new band has been 'crossband' activity ... that is, transmitting on 630m while the other stations transmit on a predetermined HF (QSX) frequency, usually on 80 or 160m. There are many amateurs in the U.S. who are interested in getting the band as well as many Canadians that are interested in getting on the band and the crossband activity usually generates a lot of interest. Both myself and John, VE7BDQ, have enjoyed making several crossband contacts this past winter and will once again be soliciting crossbanders this coming Saturday evening.

Our plan is to operate from 0200Z through 0700Z, (1800-2300 PST Saturday). Beginning at the top of the hour, we will both be calling CQ on CW and listening for any callers on HF. CQ's will continue until there are no more callers and will begin again at the next top of hour time slot. This should allow for a wide variation in propagation and the possibility of eastern contacts as the evening progresses.

The frequencies will be:

•  VE7SL TX 473.00KHz QSX (listening) 1808KHz (160m) and 3535KHz (80m)

• VE7BDQ TX 474.00KHz QSX (listening) 1813KHz (160m)

It is hoped that as many stations as possible will give a listen for us and be able to call on one of the HF QSX frequencies. Both John and myself will be running at the maximum allowable eirp for the duration of the activity.

If you have not had a look for any 630m stations, hopefully you will take the opportunity this coming Saturday night ... you really do not need any special antennas for receiving on 630m. Many of the stations that I have worked on crossband have been using HF dipoles for low-noise reception.

I'll be promoting this event on several of the reflectors and groups that I regularly enjoy and I also invite you to pass the word on to others. Please watch the blog for further updates.

See you Saturday I hope!

Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

So that’s it, I’ve broken my duck (I think those across the pond have something to do with cherries). Thanks to David, G7AGI I had an error and gap strewn QSO as part of the LIDS net. It took a little over 20 minutes to complete the basics and a bit of a rag chew at glacial speeds.

It took a lot of brain power but as I got into the QSO it got easier. The only sad point was some DQRM at the start which forced us to QSY.

A thoroughly enjoyable moment and something I’ll not forget in a hurry. Next stop the world at 50wpm!

Alex Hill, G7KSE, is a regular contributor to AmateurRadio.com and writes from Cumbria, UK. Contact him at [email protected].