QRP / K1 Video

Here's a video that I just posted on YouTube. In it I demonstate setting up my QRP station, show some of the features of my K1 and then talk a little about my QRP operating experiences. The video itself was done by John Reed K0KTY (SK) about 2 years ago.

https://youtu.be/GUk99uFMvTI

QRP Operating

Today I finally made it away for some more QRP operating. This time it was to Great River Bluffs State Park (See http://www.dnr.state.mn.us/state_parks/great_river_bluffs/ ). This park is along the bluffs of southeastern Minnesota overlooking the Mississippi River Valley. From my operating position I could see far into Wisconsin and watch the hawks soaring below me. Using my K1 and a 32' endfed wire on 14.060 I worked both K7UP, John, in Elephant Butte, NM and W2BWQ, Gene, in Congers, NY. Conditions were only fair with QSB a problem. I heard only half a dozen stations across 20 mtrs.

On the 815 transmitter front it needs a better regulated suppy for both the 815 screen and the oscillator plate. The dropping resistors have to go.

A working 815 transmitter

I have a working 815 transmitter. Unfortunately I had to "glue" a capacitor on to the side of the chassis to do it. Key to getting the final to work into a variety of loads is some sort of antenna tuner. Adding a capacitor into the grounded side of the output link does just that. The added capacitor does output loading . Tune up now amounts dipping the final with C2 and increasing/decreasing the loading with the added output link capacitor. Typical operation is 50 watts input and 35 watts out.

Eventually the loading capacitor will be hidden behind a front panel.

QRP (and a little homebrew)

After a couple of days of on and off rain with cool weather here in SE Minnesota, today was sunny and temperature about 70 ... great evening for a picnic and a little QRPing from the park. We chose to go to Florence Park in Stewartville, MN. With my K1 and 67' endfed wire in a tree, 20 mtrs sounded pretty dead. An early CQ did raise K9PWK but QSB was bad and we lost each other before we really had much of a QSO (he gave me a 229). Finally at 6:45 Terry, N4IY, in Borden, IN came back to me. We had a nice QSO. His 4 watts was doing a fine 579 job.

On the homebrew 815 transmitter front I've been trying to get the final coil wound so that the transmitter delivers full output to a 50 ohm load. At this point I'm about to add an outboard antenna tuner to my project list.

I've powered my new transmitter up on 40 meters.

For use during this test phase I built an adapter to allow the use of B&W 5 pin JVL transmitter coils instead of winding coils on my National coil forms. I'm also temporarily connecting the bias and voltage dropping resistor networks to the back 12 terminal barrier strip. This way I can easily play with the resistor values to get the right voltages.

The transmitter loads up to 40 watts input and 30 watts output with no sign of self oscillation

I've still problems, though. The 815 screen current won't come down. It appears to draw around 60 mA rather than 15. High screen current causes the screen dissipation to be exceeded, maybe damaging the 815. Right now I'm looking for another 815 to compare readings with.

A mid 30's Three Tube Regen

I aquired another radio last week. This one I "won" through ebay. The pictures posted on ebay showed a fairly ughly set with three mis-matched dials. The layout, though, suggested the "Three Tube Regenerative Receiver of Unusual Performance" by George Grammer and written up in the January 1933 issue of QST.











I bid and the gamble paid off. Underneath the flaking paint front panel and cabinet was a fairly nicely done version of George Grammer's design.







George grammer's original article was more than another construction project. He spent a large part of the article talking about features of good regen receiver design before describing "a practical receiver". This receiver includes a tuned RF stage and general coverage/bandspread tuning. Bandspread tuning is via the drum dial at the left after the detector and RF stage bandset capacitors are set. The receiver showed up in the ARRL handbooks through 1937.

815 Transmitter Coil/L1

L1 of my transmitter calls for ten turns on a 1" coil form spaced over 7/8". I had the form and the wire I needed. Winding spaced turns, though, takes a trick. I first wound the ten turn coil on the form, tightening the wire as much as possible. The turns were not even. It was not pretty. I then wound another "coil" (the red wire) forcing evenything to space out evenly over the 7/8". This I heavily coated with clear fingernail polish. After the fingernail polish had dryed I removed the red spacer coil and recoated with fingernail polish.

Picnic Table QRPing in Decorah, IA

We spent the weekend in Decorah, IA and on Saturday and Sunday I had some spare time for hamming. I used my K1 with a 67' endfed wire up in the tree above the campsite. With the K1's built-in antenna tuner it loaded up on 40, 30 and 20. Sunday afternoon at 3:00 I did finally did have a QSO with Ken, WA8REI/4. He was on the Appalachian Trail at Newfound Gap, NC near Gatlinburg, TN. We were on 14.060, both running battery/5 watt power into end fed wire antennas. With some amount of QSB, signals were around 579. For the bottom of the sunspot cycle I was pretty happy.

See more examples of my QRP operating at http://www.io.com/~nielw/qrp/QRP_Stn.htm

Final 815 Transmitter Layout

I've finally committed to a layout and mounted the major parts. From left to right along the front is the xtal (with B directly above it) C1 and C2. Left to right on top is 6V6, L2/L3, 815 and L4. RFC2 is mounted upright behind the 815 and L4. I elevated L2/L3 so that it could be mounted directly above C1. The toggle switch on top of the chassis in the right front corner is to short out L1 when not multipling in the tri-tet oscillator. The extra space along the back is reserved for whatever is needed to get the screen and oscillator voltages right. The spotting switch will probably go in the space between C1 and C2 with a cathode current meter mounted directly above it (if I add a front panel).

Final Layout / Drilling Guide

After "playing checkers" for several days tweaking the layout, I'm ready to drill. I usually mark major component locations and holes using masking tape. After I'm done the tape can be removed leaving no markings on the chassis itself.