A C-Pole Antenna for QRPxpeditions

I've finished yet one more version of my Crappie Pole antenna, this one based on KF2YN's ground independent vertical antenna (or C-Pole). See here and April 2004 QST, page 37, for more information. After trimming it a little it measures 1:1 at 14.060 MHz rising to 2.5:1 at 14.35MHz and 1.2:1 at 14.0MHz.

I found the choke balun to be key to making this antenna work. With no choke the SWR was over 14:1 at 14.060MHz and with a 10 ferrite bead choke the SWR was still 2.8:1 at 14.060MHz. What I'm using now is 15 turns of RG8X single layer wound on a 4" plastic coffee can.

This antenna is about 18' tall, self supporting without guys and has only a 4' x 5' footprint. It breaks down to a bundle 5' long. Physically it looks like a tall skinny goal post. Add a birdie and two racquets and it should fit well into a typical camping weekend.

View a video of me setting up this antenna at

https://youtu.be/nYn-GnwcSoE

Today I made several nice contacts using my K1 at 5 watts and this antenna including W8CQU in Ohio (599), WA3SLN in Pennsylvania (449), W0WCA in Colorado (449), KI0II in Colorado (549) and N4ESS in Florida (579).

This antenna is going with us when we go camping this summer. Thank you KF2YN.

Update: On June 23 I worked EA6UN on the Balearic Islands off the coast of Spain in the western Mediterranean Sea. That's over 4600 miles on my five watts and this antenna. I found Jurek calling CQ on 14.050 MHz with no responses. He came right back to me and gave a 579 report.

An SW-4 Mystery

A friend of mine noticed that my National SW-4 shown at http://www.prismnet.com/~nielw/nat_list/sw4.htm uses what looks like standard SW3 type audios as opposed to the National "Duo Coupler" mentioned in the SW-4 ad. Other National radios show a production process that used parts that were available. Close inspection and comparisons between National receivers of the same model can show undocumented differences in details. Are this audios replacement parts or do they reflect a production change to take advantage of existing stock?

As I looked at these audios I saw something else. Close inspection of my SW-4 bakelite chassis showed three large plugged holes and several plugged small bolt holes. Parts mounting and the quality of the work makes it appear that all of this chassis rework was done before most of the parts were mounted. Why all of the extra plugged holes? Was the chassis originally drilled for another product and then reworked? Was the chassis made from a piece of bakelite that already had a few holes in it? Did a worker make several errors that had to be fixed before the chassis could be used?

There are a few SW-4s still around. I wonder, do they show similar changes and reworks? Were these sorts of production techniques common or is this really a set that was carefully reworked at some point after it left the factory?

A 20 Meter Crappie Pole Vertical

This past weekend we had nice weather here in southern Minnesota....mostly sunny and temperatures around 70. I spent some time working on a new portable antenna and then using it on the air.

I was looking for something simpler than my 20 Meter Crappie Pole Vee dipole. I decided to try a quarter wavelength vertical. The March 2010 issue of QST has a good article on ground systems for vertical HF antennas. Based on that I concluded that a 1/4 wave length vertical with only 4 elevated resonant radials should perform fairly well. What I ended up with is a 16 1/2' crappie pole on top of a 4' base section. The crappie pole itself is non-conductive fiberglass. It serves only as a support for the vertical wire. The guys at the top of the base section are 14 gauge stranded copper wire. These are trimmed to resonate on 14.05 MHz and serve as antenna radials sloping from 4' at the base of the vertical to about 1' were they are each tied off with adjustable lines.

On Saturday while using this antenna and my K1 I worked WA0FJT in Independence, MO on 14.050. There was some QSB but our 5 watt CW signals were usually 589 both ways. I got on the air again on Sunday afternoon and worked WB4YXD (New Mexico), N4HUS (Arizona), W2LG (Florida) and KB2DHG (New York). All came back to my CQs on a fairly quiet/vacant band. Via email I even received a reception report from W1CTT (Maine).

The antenna seems to be fairly effective but the elevated 16' radials could be a problem, especially in a full campground or picnic area. I'll look some more for a 20 meter self supporting antenna that fits better into an average campsite

More TZ-20 Amplifier

Work continues....

More TZ-20 Amplifier

With the chassis and front panel drilled, punched and painted this project should start looking more like a kit. Everything is in hand, all I need to do is mount, wire and solder.

I laid out the chassis and front panel so that eventually this amplifier will serve as an upper deck of a 70 watt CW transmitter. My 1934 transmitter will be the lower deck/driver.

Springtime - QRPtime

With an early spring here in SE Minnesota I can start thinking about QRP again. One of my favorite local picnic table QRP spots here in Rochester is Essex Park. It has plenty of space, lots of trees with limbs about right for antenna supports and movable picnic tables. Take a look here for a video on my operating from Essex park. On Saturday I worked N1LU, Don in NH, and K1TG, Roger in CT. K1TG was an especially good QSO. We are both active in the AWA and have worked each other using our vintage stations.

This weekend at Essex Park I also worked on a new antenna. My end fed half wave and full wave wire antennas do a fine job but they require at least one well placed tree. I could use a self supporting antenna. Cabellas (and other big box sporting goods stores) sell a 16.5' collapsible crappie (as in fishing) pole. 16.5' is just about right for half of a 20 meter dipole. On Sunday I setup two of these poles to form a V to support a V (not inverted V) dipole. Read more about this antenna here. It appears to work as well as a straight dipole and it is fairly portable....now I need to find a bare nob of a hill to operate from.

National TRM 56 MC Transceiver

Last week I acquired a 30's vintage National 56 MC transceiver. Read about this model on my web site at http://www.prismnet.com/~nielw/TRM_TRW/TRMpage.htm . The TRM and the wooden cased TRW were two of the first commercially available VHF radios. At only 6"x6"x7.5" and 8.5 pounds it is amazingly heavy for it's size. The two special National transformers add a lot to the weight.

I don't find much information about the TRM. What I've found is from National's 1935 catalog and a 1933 article that, while it doesn't mention it by name, appears to describe the TRM. None of my catalogs mention the TRM or TRW after 1935 but my TRM has a model tag. National didn't but tags on their equipment until after James Millen left in 1938. This one must be a late model.

Another Swapmeet Find

Here's something that I keep around to show visitors that hams really did build the transmitters described in QST. Take a look at my version of George Grammer's push-pull TNT transmitter. This one here is a lot worse for wear but it is recognizable.

Swapmeet Find

Every once and a while over the years I've picked an item at a swapmeet just because it was interesting and if it could talk would have a story to share.

Here's one. I don't remember when or where I got it but probably at a central Texas swapmeet a few years ago. Some one on a budget wanted to get into ham radio. The local trash heap contributed an old crystal set complete with loose coupler. The tuning coil was rewound as the antenna transformer primary. Some tuning was allowed by striping off insulation in a few places. The loose coupler became the antenna coil and allowed variable coupling. I found a section of the Sunday comics shoved into the loose coupler to keep it in place..date1930. Two of the holes on the board next to the spark coil match the mounting holes for a Bunnell telegraph key.

More RF Amp

A push-pull amplifier is two tuning caps, two coils and two tubes right? With all of the support circuitry, the output loading circuit I like and miscellaneous parts and hardware it is starting to look like a real project. Once the drilling is done this one will sit until warm weather returns to Minnesota (maybe May?). I want to paint the chassis but not with snow on the ground and temperatures in the 30s.