Getting a fresh footprint on 432 MHz at the Palm HQ

I am in the process of upgrading all of my VHF-UHF antennas here at the Palm HQ and made a nice breakthrough last night on 432 MHz.  For some years now all I've had on that band is a cheesy little 6-element beam.  That's not a lot of gain, so performance wasn't great.

I've been getting emails about a Monday night weekly net on 432 MHz run by Steve, N4PZ down in Mount Morris, IL which is a 130 mile shot from me.  Since I recently acquired a 22-element boomer for 432 I thought last night would be a good time to try things out.

I assembled the yagi, attached it to a 9 foot piece of PVC, lashed it to our clothesline pole, hooked up a feed line and routed that into the house.  The SWR isn't perfect, but not bad -- I can probably tweak that a bit for a better match.

I pointed the antenna in Steve's general direction and waited for the start of the net some hours hence.  But then I noticed that Bob, K2DRH, was on the ON4KST chat so I asked if he could give me a shout on 432.100 MHz.  In the meantime I ran outside and swung the beam to point more or less at Bob.  Sure enough, a few minutes later I heard Bob in there (he's also about 130 miles from me) and we were easily able to make the QSO.  Bob thought it should been stronger but since I just guesstimated his direction it probably could have been optimized.

I swung the antenna back toward N4PZ's QTH and not long after that heard him in there calling me.  There was some fading and, as with K2DRH, I'm sure that the direction needed to be tweaked.  But it was good solid copy both ways, even with my measly 10 watts.

When that antenna gets up to 40 feet and I kick in the amplifier I should be very solid indeed on 70 cm.

The QRP2000 Frequency Generator

I'm back to working on ham radio projects and so it's time to get back to blogging about it too.

I'm still seriously into weak signal VHF-UHF-SHF work, an aspect of ham radio that I never thought would hold any interest for me but which I now find fascinating.  My goal is to build the whole line-up of W1GHZ transverters, from 902 to 3456 MHz (see W1GHZ's documentation and also the Yahoo! group I started for other builders).

To that end I have had serious need of a signal source.  Basically, if you've just applied power to a homebrewed transverter, you need to know whether it can receive something.  A simple crystal oscillator will work, allowing you to hear some weak harmonics.  But I craved something more substantial.  Now I've got it.

I settled on the QRP2000 kit from SDR-kits.  Utilizing the Si570 from Silicon Labs (mine has the A grade, LVDS chip) this unit provides frequency selection via USB control from 3.5 - 1500 MHz.  I just finished mine and it is as cool as can be.

The kit took about 2 hours to complete, including mounting in the custom enclosure highlighted at left.

The only hitch in the building process was that I received a tape of 47 ohm resistors that were supposed to be 4.7K.  I should have checked the values before stuffing them.  But I didn't and of course the board didn't work.  After going over and over my soldering and checking the polarity of diodes and such, I finally on a whim checked the resistance on a couple of the microprocessor control lines and found this mistake.  Fortunately nothing was damaged and stuffing the correct values immediately resulted in a working board.

There are a couple of software applications available to set the output frequency.  The frequency ranges for the "A" chip are spec'ed at 10 - 945, 970 - 1134, and 1212.5 - 1417.5 MHz.  Mine doesn't seem to have any of those gaps and the actual range extends beyond each end--I'm getting continuous coverage from 3.5 - 1500 MHz.


Power-wise I'm getting between -10 and -3.5 dBm out from the Si570 chip, depending on frequency.  My plan is to bolster that by 15 or 20 dB in order to be able to use this box to drive a mixer, so that I can use this dude as an agile LO for any given project.  I'll drop another little amplifier PCB in between the main board and the connector and post an update with the results.


But even without the additional gain this puppy is perfect for a signal source to check out the receive on a transverter. It puts out a nice square wave, so it's rich in harmonics.  I found that running at 100 MHz, the 15th harmonic was only 27 dB down from the main signal.  I currently have a "cheater" 902 MHz transverter at home, to get KC9JTL and me on that band for the upcoming ARRL UHF contest and the 82nd harmonic of an 11 MHz source is a welcome sign that all is well on receive.

This unit has a ton of applications, including some for my day job.  If you need a super-flexible signal source, this is hard to beat.


Next up is to build W1GHZ's RF Power Detector board.

Another Ham at The Palm HQ

 I'm happy and proud to say that we have another ham radio operator in our family.  My oldest daughter Emily took a Technician class offered by Ralph Hendrickson, KC9LBO last year.  Just before Christmas she and seven other prospective hams took their exam.  Emily passed her exam with a score of 100% and over the Christmas break she got her call sign:  KC9VEM

I'm also very proud of my son Christopher, KC9JTL, who upgraded to General at the same time.

A big thanks to KC9LBO for taking the bull by the horns and providing the instruction and motivation needed to get a bunch of new hams on the air.

The Palm family amateur radio tradition continues.

Hacking Cobra Microtalk FRS radios: Intro

Are the ubiquitous and incredibly cheap FRS radios of any use in ham radio?

I have always been really curious about that. But a Google search turns up very little in the way of hams hacking FRS radios for amateur radio uses. Well, I'm working with Dr. Cool (who prefers to remain anonymous) to do just that. We got some Cobra Microtalk FRS radios for just $2.50 after rebate. Cool opened them up to see just what's inside.

Turns out that the PLL chip is clearly marked (it's the MCD2926) and the datasheet is available. Reprogramming the PLL for different freqs is pretty simple. I even created a spreadsheet that lets you plug in a frequency and it comes up with the various command values you need to send to the chip. So theoretically, a guy should be able to push these dudes down into the ham bands by 1) retuning the VCO that's in the radio to go down about 20 MHz (from the FRS allocations, into the 430 - 450 MHz ham band) and 2) hijacking the control pins to the PLL to tell it where to go. Maybe just the first would actually get you into the ham band.

The other thing I'd like to do is to replace the VCO that's on the radio with one of the Maxim VCO parts (MAX2605/2606/2607/2608/2609, costing about $1 each). That way you'd get a nice programmable oscillator for the range of the particular VCO you select. Seems like it would be great for a small bench-top programmable oscillator or for the basis of a cheap beacon for 50/144/222/432 MHz.

We're going to keep hacking at these things, so I'll keep you posted.


[Here's the data stream being sent to the PLL chip. Won't be hard to program a little PIC processor to send that out.]

73 de W9HQ

W9HQ on Transverters in QST Magazine

I recently worked with Paul Wade, W1GHZ, to have a little blurb in his Microwavelengths section of QST magazine. This year I have resolved to get serious about finishing up at least a few of my W1GHZ transverters, hopefully in time for the August ARRL UHF contest. Working on these projects is exciting and educational. I started a Yahoo! group for other builders and it has almost 100 members now, with a nice boost from the QST article. Here's what I wrote:

UHF and SHF weak-signal operation is an aspect of ham radio that held no interest for me, until recently. Now, however, I’ve been totally hooked by this new frontier in radio. The circuits needed to generate such high frequencies have always been mysterious to me and the technical challenges and sometimes esoteric materials involved discouraged me from seriously pursuing any sort of equipment building.

Fortunately, the levels of integration available in individual RF parts capable of functioning way up into the GHz levels is such that the really hard work has been done for us. The amplifier, mixer, and filtering blocks are cheap, readily available, and highly optimized. What’s left is combining these building blocks into a design capable of operating in the ham bands.

The transverter circuits created by W1GHZ are delightfully simple and just examining the schematics and reading his description of how he designed them is an excellent tutorial in transverter operation. Fundamental operations such as frequency multiplication, filtering, and IF/LO mixing suddenly become clear when confronted with such a clear and basic design. Once you understand Paul’s simple designs, more complex transverters suddenly become clear. They all work the same way!

Aspiring builders can get the PC boards from W1GHZ, but then you’re on your own to acquire the necessary parts from various sources. A fine pointed soldering iron, a little magnification, and a steady hand are all that are needed to stuff the small surface mount parts to the boards. But this is not kit building, so definitely not for the beginning builder. There are no part by part instructions on how to assemble these boards and the means of final check-out is entirely up to the individual. That brings up a potential obstacle for some builders. At least in my opinion, check-out of the modules would be very difficult without at least some access to a spectrum analyzer. With an analyzer I was able to bring up the 1152 MHz LO for the 1296 MHz transverter and found immediately that, although it was oscillating, its output was extremely low. Working back over my board revealed that I had misconnected one end of the bias resistor to the final amplifier stage. A quick rework brought the LO up to its desired output. I can’t really imagine how I would have found something like that without a spectrum analyzer.

I’m learning incredible amount both in theory and practice by building my W1GHZ transverter boards. I can’t wait to get one on the air—that first contact with a SHF transverter that I built myself will be thrilling indeed.

Those interested in joining an on-line group dedicated to building W1GHZ transverters are encouraged to visit http://groups.yahoo.com/group/w1ghz-transverter-builders/

First Aurora QSOs Ever!

This afternoon I got the word via e-mail that there was an aurora opening on 6 and 2 meters. I spun the antennas north, fired up the IC-746 and listened. Sure enough, there were those strangely garbled CW signals coming in here and there. I listened for a while and answered a couple of CQs. I was able to work first N0SM in EN30, about 200 miles south of me and then W0RT in EM27, about 500 miles south of me. That's communicating hundreds of miles to the south......while the antenna was pointing north! How cool is that?

73 de W9HQ

QRP for Field Day 2010

Other commitments kept me from joining one of the local groups of hams for Field Day this year. But it just so happened that I got an FT-817ND in the mail that Saturday morning. Obviously, I had to try it on the air and Field Day seemed like a perfect opportunity.

I connected the rig to a battery/solar panel combo and my off-center fed Windom antenna. This is the first QRP rig that I've owned, so obviously I'm no expert. But between this and my experiences in VHF-UHF contesting here are a few of the things I found about making contacts in less than ideal situations.

I made contacts on 40, 20, and 10. 10 was great when it was open, because there was so little QRN. One thing is to try and maximize opportunities on the higher bands when they're open, because a QRP signal will really shine because it doesn't have to overcome S6 or S8 noise. 6 meters has been open a lot lately and you can do fantastic things with 5 watts on 6 meters. 10 meters is great this way too. And the antennas are very manageable. I built a little 2 element beam for 6 meters, turn it with a small TV rotor, and it has performed wonderfully for me.

During Field Day I made most of my contacts on SSB, a few on CW. 20 meter CW was an absolute zoo, so I didn't even bother. But in general, CW and QRP are a match made in heaven. CW is good for at least 10 dB in readability, especially in less than ideal band conditions, so you've made up most of your 12 dB difference between 5 watts and 100 watts right there. I was fast back in the day, but I can only clunk around now at about 10 wpm--but it's really a lot of fun and guys will slow down for you. So if you don't already do it, I'd say learning Morse code will give you a lot more satisfaction out of your FT-817 or any QRP rig.

Now on SSB, a lot of guys have commented on the fact that the FT-817 lacks a speech processor. Okay, well that add-on is a little too expensive for me so I just do my own speech processing. I yell into the mike, at least in Field Day type conditions where I'm trying to break a pile-up. Pretty much literally shout into it. And I raise the tone of my voice, so that the higher pitch makes a more readable signal at the other end. My son, KC9JTL, speaks too quietly into the mike and keeps the pitch of his voice too low. He gets frustrated during contests that stations will answer me and don't him. Well, that's because I raise my voice. And I get the contacts. But if you're willing to part with more cash to deck out your FT-817, I'm sure a speech processor would be a nice addition.

I signed QRP in my calls and several of the operators heard and cleared the way for me. "The QRP station, go ahead." Let's face it, a weak signal that is just a weak signal is uninteresting and difficult to work with. But a weak signal that is weak for a reason--either because you're QRP or because you're doing VHF-UHF-microwave stuff and you expect it be weak--well that's all of a sudden interesting to a lot more guys. So I'd suggest signing QRP after your call when calling CQ or trying to break a pile-up. Some guys will perk up at that and take the extra effort it takes to copy your weaker signal.