W1GHZ 1296 MHz RX working!

November 19th, 2010 by k8gu No comments »

I spent about two hours last night assembling the W1GHZ 1296RSU and 1152LO boards from his paper “Multiband Microwave Transverters for the Rover—Simple and Cheap.”  Once again, I trekked over to W3APL beacon site at lunch and put the pair through their paces on RX with the IC-290H as the IF radio.  It worked!  Here’s a clip:

W3APL_B_1296MHz_FSK_mono

One of the interesting things about the 1296-MHz beacon is that it’s FSK, not CW.  You’ll notice this after about 15 seconds when it starts sending its callsign.  The higher pitch tone is “keyed” and the lower is “unkeyed.”  Brian, ND3F, was at the beacon site with us last week to check out a problem (turned out to be a dead power supply fan).  He told us that it’s common for microwave beacons to operate in FSK mode so you always have a carrier to tune across (and swing your antenna across).  Who knew?!

Anyhow, it’s time to start building the other trappings, including enclosures, sequencers, filters, PAs, and T/R switches!  Apart from the PA parts and some connectors, the other components are on-hand and ready.

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Raytracing

November 19th, 2010 by k8gu No comments »

Today we have a little bit of fun ham-related tinkering from work.  This is two different frequencies transmitted from the same site.

There are lots of neat details in a ray-trace:  skip focusing, Pedersen rays, mode-splitting, …  One thing that’s fun about writing your own models is that you can modify (intentionally or not) the model physics to do unphysical things…

The second run shows X and O modes for a single frequency and a failed attempt at modeling an MF signal into an E-F region duct.  (The ducting, by the way, has nothing to do with my actual work.  I was simulating it for ham purposes, although it helped me uncover a problem.)  The signals do get to the duct, but they bend the wrong way.  This has been fixed in the code, but it serves to remind that modelers have complete control.  The background ionosphere is relatively unphysical in this one as well…

The raytrace code used above is small, simple, and written in MATLAB.  I doubt that it will ever be released publicly, but if so I will note it here on the blog.

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A Follow-up to “New QSL card”

November 19th, 2010 by k8gu 2 comments »

This is a follow-up to a post from Sunday.

On Wednesday night, Sarah handed me an envelope from the day’s mail that had the appearance of a QSL card.  I took out my knife and opened it.  It had a some sample QSL cards, along with a brochure inside.  I scratched my head for a moment and concluded that I had just received my first QSL card for a blog post.

This curious turn of events brings me around to a couple of points.  For those of you who don’t know, this blog is aggregated by AmateurRadio.com (and it is syndicated on my Facebook profile).  My agreement with the owner of AmateurRadio.com is that he provides me with visibility in return for select content from my blog.  The QSL printer who sent me the samples is one of his advertisers.  Thanks, by the way!  The cards were very beautiful and of high quality and I will consider him to print photo cards for my next DX operation.  In full-disclosure, I received nothing from the printer who printed my cards in return for mentioning them.  But, I should clarify that the blog is something I do for fun and I’m not really in the business of product endorsements.

A final point of clarification is that my beef with the available QSL cards was not so much the quality available, but amount of semi-relevant stuff hams try to cram onto the card.  I guess if 10 meters ever opened up again regularly, we might start getting asked for our “Ten-Ten” numbers again.  After listening to the V31BB clip about the secret decoder ring, I’m sort of ashamed to admit that I have one.  Strike that from the card!  The long and the short of the original post was that I wanted an uncluttered, distinctive card.  And, I think I found it.

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W1GHZ 903 MHz RX working!

November 16th, 2010 by k8gu No comments »

Although I built the W1GHZ 903-MHz transverter and 756-MHz LO boards last winter, I didn’t have time or inclination to test them until this week.  These were purchased as a part of the first (October 2009) group buy orchestrated by W8ISS.  Instead of the INA-10386 MMIC recommended by W1GHZ, the W8ISS kits featured a Sirenza SGA-3586Z MMIC as the LNA, as suggested by the 4s_microwave group.  A better part (with NF < 2 dB), recommended to me by W9SZ, is the the SGA-4586Z, which I used on my 903 board and will use on my 1296 board.  This requires the bias resistor (R3, 51 ohms, on the 1296 board) to be changed to 100 ohms.

Since there is a lot of foliage between me and the W3APL beacon, I took the liberty of carting the transverter and IF rig to the beacon site (sorry no photos) on my lunch break yesterday.  Sure enough, it worked like a charm with the beacon pounding in on 147.0615 MHz.  The nominal beacon frequency is 903.055 MHz, so I don’t know if the difference is in my LO or the not-GPS-locked beacon drifting around.  At any rate, I’m pleased enough to continue the project…

The 1296RSU transverter and 1152-MHz LO boards are on the left in the photo above.  They have not yet been populated, but that’s an evening’s work.

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New QSL card

November 14th, 2010 by k8gu 3 comments »

As I have bemoaned in the past, good QSL card designs are hard to come by.  This is my attempt to remedy that situation.  The front has my callsign, with a QR code linking the interested recipient to this web site.  The reverse is postcard-friendly with space for six QSOs, corresponding to 1.8/3.5/7/14/21/28 or 50/144/222/432/903/1296 MHz.  The address space can be used for a personal note if the card is mailed in an envelope.  The card is also QTH-unaware.  This means that I’ll have to write or sticker my way along, but I won’t be limited by my moves and travels.  The font is Gil Sans everywhere.  The cards were laid out using Adobe Illustrator CS4 and printed on 100-lb matte cover stock by Carlisle Printing, who printed my last cards as well.

One final note:  one week after SS CW, I am already up to 43/50 states for my CW WAS from Maryland using LoTW.   I’m not sure how many of these QSLs will actually make it into circulation at this rate.  Be sure to work me so you can have your own copy of this rare collector’s item!

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CW Sweepstakes 2010

November 8th, 2010 by k8gu No comments »

(Image credit:  via contesting.com)

After missing the two contests that I hoped would kick off my contest season, ARRL Sweepstakes was next on the list.  I managed a decent showing that would have won the MDC certificate for A-power last year, provided the log-checkers don’t take too much.

Highlights (“Wins,” as we like to say on #wwyc):

  • 80 meters was awesome.  Good conditions and the K9AY helped me keep the noise under control.
  • Everything worked for the most part and everything still works after the contest is over.
  • SO2R CW with TRLog.
  • Working lots of old friends from my time in MRRC, MWA, and SMC.
  • Working lots of new friends from PVRC.
  • Getting my receiver crushed on all bands when I tuned across W4EE who lives less than a mile away.

Lowlights (Fails):

  • RFI to the CO detector waking Sarah up in the middle of the night.  KA9FOX and AA9DY have had this problem.
  • Not spending enough time on 15 meters and missing VY0JA and VY1EI there.  Missed the sweep by 1.
  • Not being able to answer people responding to my main radio CQ while working someone on the second radio.  This only happened about five times.  But, one of these was my Bureau sorter!  Sorry!
  • Getting confused for K1GU a few times.

Here are the numbers…thanks to all for the QSOs.  See you again in two weeks on phone with a different callsign.

ARRL Sweepstakes Contest, CW

Call: K8GU
Operator(s): K8GU
Station: K8GU

Class: Single Op LP
QTH: MDC
Operating Time (hrs): 17
Radios: SO2R

Summary:
 Band  QSOs
------------
  160:
   80:  367
   40:  243
   20:  100
   15:    0
   10:
------------
Total:  710  Sections = 79  Total Score = 111,548

Club: Potomac Valley Radio Club

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W3LPL-inspired 160/80 RX splitter

October 25th, 2010 by k8gu No comments »

In an earlier post, I described my K9AY loop system.  QRX for an update on the outdoor portion.  But, after returning from a short and much-needed vacation at the beach yesterday afternoon, I whipped-up this little guy:

One of the big problems I have living in the city is overload from broadcast stations in the AM band.  (This is especially true in the heavily-populated, full-of-hot-air DC area—Ed.)  But, I digress.  I also wanted to protect the preamp and receiver when I was transmitting on the higher bands into nearby antennas.  So, some sort of filtering was in order.

I contemplated a number of topologies.  But, the W3LPL filters were a good choice because they’re cheap and very good.  A good reference on what I did is the NCJ article by K3NA and W2VJN about the VP6DX receiving antenna system.  The Ducie Island system is considerably more complex than mine.  But, they had more stringent requirements, more land for Beverages, and more money than I do.

Following the K3NA/W2VJN/W3LPL topology, I constructed a little diplexer filter for 160 and 80 meters that splits my K9AY to two receiver ports.  This splitter is the first thing after the K9AY coax passes through the station ground bulkhead, requiring a preamp on each port.  Since I don’t have a TX antenna for 160 yet, that port will go to the SoftRock-160.

I’ve only tested the 80-meter portion (since I didn’t get the 160 portion done until this morning before work).  But, it works like a champ and there is no overload from broadcast stations.  Although there are some curious mixes coming from some of the big AM stations in the area that seem to be external to the receiver (this has been confirmed by N3OX—pretty amazing stuff); but, that might deserve its own post at a later date.

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Keyboard Trays, QRP Rig, and SoftRocks

October 18th, 2010 by k8gu 2 comments »

Time, as they say, has been of the essence of late.  So, when I do have time to play radio, I rarely have a chance to write about it.  Here are some photos of my latest tinkerings.

Keyboard Trays

Sarah has always talked about using a keyboard tray at work as a part of an ergonomic workstation.  Until recently, my work invovled enough variety of computer and non-computer time that I did not think about it.  But, after coming home from work with stiff shoulders and wrists, I decided something should be done.  While I was at it, I upgraded the HF and VHF/SDR operating positions at K8GU with pull-out trays, as well.  These were $10 each at IKEA and pretty easy to install, although I told Sarah that I was grateful that she didn’t witness my contortions to hold them up with my knees while driving the first screws.

Liberating my inner QRPer

Back in high school, I built a Small Wonder Labs SW-40 that I had seen in a QST article.  It lived in a variety of enclosures, but spent the last decade in the ugly PC board half-enclosure that looked like a redneck pickup truck at right.  I decided to put it into a proper enclosure, being the diecast box at left.

Despite the fact that I made the radio impossible (no room for front panel controls) to assemble the first time I drilled the board mounting holes, I’m pleased with the result.  Four dabs of gray epoxy cover the errant holes.  I probably could sand and polish those now.  The power connector is a pair of Anderson Power Poles.

VHF Softrock and Enclosures

Readers of the blog have seen the screen capture from my new Softrock Ensemble II VHF.  Tony does not advertise these on his site because they are not 100% supported with documentation yet.  Robby, WB5RVZ has done a great service to the community by preparing step-by-step instructions for most of the SoftRock series.  I’m not a step-by-step kind of guy, so I just used his photos showing the locations of the 0.1 uF and 0.01 uF chip capacitors and built the rest my way:  mount all chip caps, all SMT ICs, all through-hole ICs and sockets, all through-hole resistors and diodes, all through-hole capacitors, all inductors, and all connectors.  It worked right away.

I also have two v6.0 SoftRocks that I built a few years ago while I was in grad school.  One of these (for 160) has been a bare board all these years and the other (for 40 and 80) has been living in an ugly little RadioShack black plastic project box.  I decided to upgrade them to diecast boxes with external power connectors (also PowerPoles—I’m slowly switching the station over) and a switch for 40 and 80 meters.  Here’s the happy family of little radios…

The 160-meter SR v6.0 is on top of the diecast box holding the SR v6.0 40/80.  The Ensemble II VHF is on the right.  It’s unfortunately too long for either size diecast box.  I don’t like the commercially-available box for it.  So, we’ll have to see…

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Bureau Cards

October 18th, 2010 by k8gu No comments »

If you have come to the site checking to see if I am still alive because you have not received a QSL card via the bureau system, you have come to the right place.  I finally mailed about four years worth of CE/K8GU, KP4/K8GU, PJ2/K8GU, and K8GU bureau cards out this week.  (Yes, it was a nice-sized pile, but not as big as it could have been.)  There are a few recent requests that have not been filled because I ran out of CE/ and KP4/ cards.  I will get some more soon.

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144-MHz SoftRock

October 14th, 2010 by k8gu No comments »

144-MHz SoftRock Ensemble II VHF by KB9YIG and VE3NEA Rocky 3.6.  Yup, that’s W3APL/B (off the back of the beam) and WA1ZMS/B in the same waterfall.  How cool is that?!  More later…  This has many implications for many projects!

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