I've temporarily put aside the variac box I wrote about earlier in the week, to switch over to the antenna project I wrote about last month. Why? This project has a deadline of sorts, a major ham radio operating event at the end of this month. I need to get the antenna built and begin testing it to evaluate its performance and that's a priority. Within a week or two, I'd like to know how it works on both bands it was intended for and know how it compares to what I have.
Yesterday, I cut all the PVC and glued it up.
This plastic storage bin on the back porch made an acceptable workstation. I carried my Metcal soldering iron out there and kept adding more tools as the afternoon went by. It was in the low 50s and breezy all afternoon which felt a bit cool to me. The sun peaked out now and then making it comfortable, but I ended up wearing a wind breaker over a long sleeved Tee shirt for most of the work.
The K9AY antenna uses a terminating resistor (at right) and a matching transformer (on the board on the left). The terminating resistor's value by what's marked should be 490 ohms, but measured closer to 520. The actual optimum value is probably a bit lower, and that's probably an experiment I'll be doing. Everything is unprotected from the elements, just bare soldered wire and parts so that I can get to that resistor or to the transformer, should I need to change that. Another reason for the deadline date on this project.
The slow part about today was that I hadn't looked into the details
well enough to have parts prepared and ready to mount, so finding
resistors, winding and testing a transformer, then cutting and drilling
the plexiglass was part of the day.
Tomorrow will be time to feed the coax through the wall feedthrough into the ham shack and begin the evaluations. The resistor and feed polarity give the antenna a direction; I believe the "front" is on the left in these pictures, but that's the first thing to determine.
I'll have to Google that callsign and see what it reveals!ReplyDelete
I finally found a weather resistant case at the local Grainger, and now that the garage is pretty well cleaned-up, I can proceed with getting the SGC-230 installed in the case, and my 33' vertical back in service.
When it was in use in Long Beach I left two sections out, which made it a 5/8 wave antenna on 10. This time, with 10 Meter openings getting sparse, I'll put all of the sections together and have a quarter-wave on 40.
K9AY is Gary Breed. He used to be the editor of RF Design magazine, then started High Frequency Electronics and RF Technology International. Somewhere in there, back in the late 80s/early 90s, he had the idea of breaking the trade magazine paradigm by making a by a subscription supported magazine instead of purely advertising supported. That flopped, and I think that's what became HFE.Delete
I downloaded a bunch of articles on the antennas; they're very popular with the 160m crowd. If you want to email me at this SiGraybeard gmail account, I'll send you what I collected.
Same for anyone who asks.
Just curious, what is the operating event at the end of January you are participating in. I have ruled out the Jan VHF contest and the 160 M CW contest.ReplyDelete
The Bouvet Island DXpedition.Delete
Yes, much like you do at the famous 12 step programs, I step forward and sheepishly confess, "I'm a DXer".
The antenna doesn't work At All. WWV is about 70 dB weaker on it. As they say in Miami es Muy FUBAR.
Time to take stuff apart and troubleshoot.
And if anyone is interested in 160M, I saw an interesting antenna for small lots - a helical wound vertical on 30 ft. of PVC.ReplyDelete
I need to build one real soon now. :)
I've seen similar "short" verticals before. A guy From 9-land I knew very well, Barry Booth, came up with one design, and it worked quite well.Delete