Mariana Islands DX Association - PO Box 445 - Agana Guam 96932
 
 
Volume 2 Number 3 - July 1999
Edited by KH2D
Published Quarterly by MIDXA
Email Items to MIDXA

IN THIS
ISSUE:

Club
News

QRP ?

PSK-31
Hot New Mode

MIDXA
Field Day

 

 

Club News
Congratulations to KH2JU on his upgrade to Advanced. Now if we could only teach him a foreign language, he'd be ready to try for his Extra.


QRP Anybody ? by KH2D

I got the box out of the closet a few weeks ago that's marked 'KITS'. Seems I buy a few kits here and there but never put them together. Anyway, I decided it was time to get the soldering out and see if it still worked.

A couple years ago when we were making an effort to get those 'other guys' interested in HF, I bought a few kits from Ten-Tec. One was a keyer, which I built as soon as I got it, but never put it in a case.. Nothing fancy, just your average 12 dollar keyer. The other kit I hadn't built yet was a 20 meter transceiver, the 3 watt QRP model. So I figured I'd give it a shot so we could try QRP at the beach for Field Day this year.

The kit cost $95.00 which includes EVERYTHING you need to build the radio except solder - case, hookup wire, the whole nine yards. The circuit board is extremely good quality, with plated thru holes - which can be a pain if you need to unsolder stuff. First thing I did was sort out the parts, all 219 of them, and stuck them in a hunk of styrofoam for easy access. Here's what the mess looked like at the beginning of the project:


Click for bigger picture

The manual, the circuit board, and most of the parts. The manaul is pretty good, but there are two or three 'erata' sheets that came with the kit - fixes for mistakes in the manual, and a few changes.

I'm careful when I build stuff, I scrape all the component leads and verify resistor values with a meter (which saved me a couple mistakes) and the kit took me about a week to put together, working on it evenings (and a few all nighters). Probably at a leasurly pace it would be about a 2 week project if you take you time and work on it a few hours every evening.

The kit is built in eight steps (sections) of the radio and one of the really nice feature is that there is a testing process at the end of most steps that lets you verify that the section you just built works. Started out with the keying circuit, then the VFO, the transmit mixer, etc. No fancy test equipment is needed, an analog volt meter and another radio with a dummy load (or an antenna) are about all you really need - and in my case, the magnifying light (so I can see the parts).

Anyway, here's what it looked like after a week or so and it was all ready for testing on the air:


Click for bigger picture

I guess the most difficult part of the project was winding coils - there are five coils that you have to wind around torroids - one for the VFO and four for the transmitter final. The VFO coil determines the tuning range of the radio and is very touchy - when you get it finished you need to nail it in place - I covered mine with Super Glue once I had the tuning range where I wanted it. I found I had to add one extra turn to the VFO coil than what was suggested in the manual. The finished radio covers from 14.008 to 14.074, which is about the range the manual suggests it will tune, but you can build it for any section of the 20 meter band you want to.

After I peaked the transmitter, I was tuning around to see what I could hear and DS1BHE was CQing near the bottom of the band so I called him - and got a 579 report. So I guess three watts works.... Here's the finished project (next to a Super CMOS II memory keyer I built the week before the QRP rig):


Click for bigger picture

The receiver seems to work great - the JA's are LOUD and the night I finished the receiver section I was also hearing a bunch of loud stateside stations who were working K4SXT/KH2 in the middle of the band. I still seem to be having a little RFI problem with the transmitter (go figure, 3 watts and RFI problems?) but I'll fool around with the thing and see if I can figure out what's causing that. Anyway, look for the little black box on the table at Field Day...

Ten Tec makes the radio for 20,40, or 80 meters and their web page says the 15 and 17 meter versions will be out soon. Price wise, I think it's probably the best QRP rig around.


MIDXA Field Day - 1999


N2NL at the controls, KH2D as the sun glasses,, and KH2JU watching.

The Guam gang did Field Day this year at WH2U's beach in Talofofo, despite the bad weather. Sunday was a rainy, humid, yucky day but we showed up in the morning anyway and put our 5 element 20 meter quad up in the trees. Propagation, as predicted was not great during the day, but by about 4 PM in the afternoon, we were working some stateside stations and were even amazed that our CQ's were being answered for the first time in many Field Days...... We used KH2JU's Icom 735, and battery power for the station. The late crew, KH2JU, WH2U, and KH2D got so busy they were logging with a portable computer. The PDN reporter came by in the afternoon, so we managed to get our picture in Monday's paper for some publicity and some bonus points. KH2JU was in charge of the cooking, and despite the bad weather and lousy propagation, a good time was had by all.


PSK-31, Hot New Mode ?

If you get the ARRL email newsletter, or you've been reading their web page, or you've been banging around on Usenet, you've probably heard the term PSK-31. Everybody's yelling and screaming about ham radio's hotest NEW mode.

WHAT IS PSK-31?
First off, PSK-31 isn't really 'NEW', it's about 3 years old. It's an unconnected, no error correcting mode, like RTTY. You type, the radio transmits, and you hope the other guy gets what you typed. The other guy types, his radio transmits, and he hopes you get what he typed. Kind of sounded just like RTTY to me, so I wasn't too sure why everybody seemed so excited about it and I didn't rush right out to join the crowd using it.

The reason it's being advertised as 'NEW' is because there is now some Windows software which allows everybody to use it, and that's fairly new. PSK-31 was invented by Peter Martinez, G3PLX, who happens to be the same gentlemen who invented AMTOR. It's a keyboard to keyboard chat mode, not intended for file transfers but for QSO's, and it uses the Varicode character coding at 31.5 baud, or approximatly 50 words per minute. One of the things that I have noticed about RTTY over the years is that you needed to be receiving a fairly strong signal to copy much, and RTTY is very subject to interference from other noise on the band. RTTY works best, for me anyway, in the FSK mode with a CW filter, and not very well in the AFSK mode..

WHAT YOU NEED TO DO PSK-31
You need a computer running Win95 or Win98 with a sound card, and most of us already have that. Then you need a hardware interface from the sound card to the radio - like the one on the MIDXA web page that we built for our Digital Voice Keyer. Once you have those two things, you need to download the software from the PSK-31 homepage on the internet. The program is fairly small and doesn't take long to download. There is a manual in HTML format on the web page you can download also. The program is not fancy, but it's easy to use and works very well. There is no transmit buffer, so you have to type in real time as you transmit. But that problem has been fixed already too, by WD5GNR. He has written a Visual Basic program that is a 'frontend' to G3PLX's PSK-31 program. It includes a type ahead buffer, macros, and the usual stuff you'd see on a RTTY program. You can download it from the WD5GNR homepage. Both programs are freeware, no charge, for amateur use. A PSK signal sounds like a watery carrier, on the PSK-31 page there are a few audio files you can listen to and hear it first hand. The twenty meter frequency is 14.070.50 so tune around there to hear PSK-31 on the air.

HOW WELL DOES PSK-31 WORK ?
I've been using it for a short time, just a few days, but I'm pretty impressed with the performance. I'm not a big RTTY fan, so I don't go jumping up and down about keyboard to keyboard QSO's, but PSK-31 has some pretty amazing features. It uses very little bandwidth, only 30 hz. Which isn't much. And since it's so narrow, along with the way it's designed, it doesn't require an S9 signal to work. Matter of fact, believe it or not, it doesn't require a signal you can HEAR to work. I've worked a bunch of guys in the U.S. with PSK-31 so far, and I've done some SWL'ing also. Most of the guys I worked were using dipoles or verticals, and 30 to 40 watts. Most of them were S1 at best, a few on the west coast a bit stronger, and a few of them no S meter reading at all. I have been running about 35 watts output with PSK-31. I have tuned around and found two stations talking, and when the one I found was done transmitting and the other one started, I was surprised at times to see the words printing on the screen even though I could not hear the station who was transmitting at all. Most of my QSO's and SWL'ing have been 95% solid copy, which is a much better rate than I've seen from anything that does RTTY. With the exception on one contact. JA5TX called me and he was about 589. I couldn't copy ten percent of what he was sending, and we tried for 20 minutes. The documentation by Peter explains why PSK-31 is not a good mode for HF paths with any flutter on the signal, and the path from KH2 to JA at night seems to verify that he's right beyond a doubt. I heard a bunch of JA's, but I couldn't find any that I could copy very well, irregardless of signal strength.

IS PSK-31 EASY TO USE?
Yes, very. Since the signal is only 30 hz wide, tuning is VERY CRITICAL. But the program has a graphical tuning indicator which lets you tune things just right. You can't tune to a 30 hz resolution with any ham rig, no matter how new it is, so you get as close as you can and go the rest of the way with the software. You need a stable radio, I wouldn't recommend an FT-101, but it might work. Spend a few mintues reading the help file Quick Start, and you should be ready to go. Remember than since you are transmitting a constant tone, your radio is close to a 100% duty cycle (like RTTY) so you want to crank the power down to 30 or 40 watts.

MY IMPRESSION OF PSK-31
As I said before, I'm not much of a RTTY fan, keyboard to keyboard QSO's have never gotten me real excited. Since the software sets your transmit signal to exactly the same frequency as the signal you are receiving, it's not much of a 'pileup' mode either, as everybody listening will be on the exact same frequency. I don't think it was intended for pileups or for contests. But PSK-31 seems to be more fun than RTTY for me, probably because I am copying a much larger percentage of what the other station is sending than what I'm used to with RTTY. I don't think I'll be working on PSK-31 DXCC or WAS, but it will be something that I'll pull out now and then and play with. Seems to be quite a bit of activity, I haven't had any problem finding other PSK-31 signals on 20 meters, so plenty of people around to 'talk' to.

It's 1999 guys, and if you have a soundcard and a computer, and you aren't using it for ham radio, you are missing a bunch of stuff that's fun to play with. You're missing Slow Scan TV, you're missing DSP audio filters, you're missing DVK software, and now you're missing PSK-31. Go build the soundcard interface for your radio, and I'm sure you'll be glad you did.

73, Jim KH2D


Club Activities
Guam
Breakfast as usual at Shirleys in Harmon on Saturday mornings, at 11 AM. We tried the food court at Micronesian Mall, and also Shirleys in Magnilao, but we're back home to the usual spot. The mall was too noisy and Magnilao was, well, a bit slow......

Saipan
The Saipan guys did the Tagaman Triathlon again, unfortunatly nobody from Guam could attend this year due to other commitments.


 
   

Pacific Radio Waves is published quarterly by the Mariana Islands DX Association.
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