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Wednesday, December 25, 2013

KX3 Filter Settings for SSB, CW and Data

While setting up for the AWA '29 QSO Party I started playing more with the KX3 filtering and audio response....mostly because 80 meters seemed particularly noisy that night. I found something that really helped me see the interaction of the various receive selectivity options: Rcv Audio Equalization, Notch, APF, Data/RTTY mode, Passband Width, Passband Shift and Passband Hi/Low Cut.

I downloaded DigiPan from (Freeware) onto my laptop, not for the PSK31 function but for the waterfall. I then configured DigiPan to use my laptop built-in mic as the audio input/source. With my laptop sitting next to my KX3 I tuned to a unpopulated but white noisy frequency. This may require the preamp to be turned on. While watching the white noise on the DigiPan waterfall I tweaked the various filter settings. The white noise waterfall display changes to reflect the filter settings, clearly showing me the impact of what I was doing. SSB, CW and data signals can even be tuned in and viewed as the various selectivity options are changed. The KX3 CWT Aid and the Filter Passband Graphic show some of this but not to the detail of the DigiPan waterfall.

For example here's a sample waterfall showing the impact of narrowing the KX3 bandwidth setting followed by adding the Audio Peak Filter (APF). The horizontal scale is frequency (in Hz) and time is the vertical scale.  The CW signal of interest is the yellow streak at 520Hz. Interference is the yellow (stronger) and blue (weaker) around the 520Hz signal.

Friday, December 20, 2013

1929 BK QSO Party

The past two weekends I spent 4-5 hours operating in the BK. I had 16 QSOs
and worked five states including NC, MT, MI and ME. Background noise levels were pretty high but even with about 2 watts out I still made contacts.

I'm not pleased with the way my TNT transmitter sounds on 40. After an initial excursion into that band on Dec 7 and then critically listening to my own signal I decided to stick to 80.

Friday, December 6, 2013

1929 BK QSO Party

I'm set up for the AWA Bruce Kelley 1929 QSO Party. This year I'm using my TNT transmitter with two 45 triodes in push-pull .  This transmitter has an output of only 2-3 watts with 10 watts input, about typical for self excited oscillators like this connected directly to the antenna. At first I thought I'd also use a vintage receiver but I switched to my KX3.

Tonight I did work KK4HCF in TN and WA1KPD in CT  heard me so there is hope for the QSO Party.

Friday, November 15, 2013

More about a power supply for a 1939 Transmitter

Plans change....after studying my collection of available transformers I found one rated at 560 (center tapped) at 270mA. This would work well with a full wave bridge rectifier as the TZ-20 final stage B+ (550VDC). Half of this, full wave center tapped rectified, is about right for the buffer stage (270VDC) and a VR-150 should be able to take this down to 150V for the oscillator stage.

I recalled Brian, WA7PAC's, comment to me several years ago when I was
dealing with a similar problem on a different transmitter. He suggested an "Economy Power Supply". Rather than clone my one transformer it's possible to run it with both a full wave bridge rectifier and a full wave center tapped rectifier.This looks like it may work.

I'm using PSU Designer II to help me play with filter options before I put solder to the iron.

Wednesday, November 13, 2013

A power supply for a 1939 Transmitter

With my KX3 n the shop because of a bad output transistor and cool weather returning to SE Minnesota I'm again in the basement looking at boat anchor projects. One project on my list is to clean up the power supply for my 1939 transmitter. Right now I've borrowed the power supply from my 1951 novice station to power the oscillator/buffer stages and used a second 500VDC supply for the TZ-20 amplifier stage. Needless to say, these don't show up in my blog photos of the transmitter.

My new power supply is a pretty brute force design delivering 550VDC, 300VDC and 150VDV to the transmitter using two power transformers, a couple of 5R4 rectifiers, a VR-150 and the needed filtering circuits. It will be two fairly heavy supplies on one chassis.

I found all of the transformers and components in my junque box but not a stout enough chassis for all of the iron. I turned to my slat board design to take care of this shortage.

Monday, October 14, 2013

Boots for a KX3

I finally got the relay box finished so that I can use my grounded grid 572B amplifier with my KX3. On receive it bypasses the amplifier and delivers -100VDC cutoff bias. On transmit the 572B grid is grounded and the KX3 output is routed through the amplifier.

Lacking a triple pole-double throw relay I used a double pole-double throw relay to transfer the antenna and a single pole-double throw relay to switch the cutoff grid bias. The two relays run off of 12 VDC but together require about 1/2 amp, way more than the KX3 Keyline Out line can handle. A "Keyall" board from Jackson Harbor Press/WB9KZY solved that problem. Ideally I would have used a single transformer that delivered 12VAC and 100VAC for the two supplies. Lacking the ideal I used back to back 12V transformers. One toggle switch was added to allow manual send/receive control without the Keyline Out signal from my KX3. Another toggle switch was needed to power on/off the 12V/100V power supply.

When I use the relay box and my amp, the KX3 antenna tuner has to stay in the circuit in order to match the transceiver to the uncontrolled input impedance of the amplifier. In addition the antenna relay can not follow break-in CW keying without losing the first dit so I must use the KX3 in PTT mode. On the plus side I run about 80 watts to the antenna instead of 4, maybe not a big deal for CW but real help for SSB.

Wednesday, August 14, 2013

A Nice Day in Minnesota

Today, with nice weather and nothing on the calendar,
Beth and I headed for Frontenac State Park, one of my favorite places for picnic table QRP. The picnic area at Frontenac sits on a bluff overlooking the Mississippi. The view is great, the trees are plentiful and there's nothing to get in the way of my signal.

Sunday, August 11, 2013

SOTA Trip to Steptoe Butte

On Sunday, August 4, I went a little beyond my regular picnic table QRP sort of laid back operating. With some spare time while visiting in eastern Washington, I decided to do a SOTA activation of Steptoe Butte.

Summits On The Air is an award scheme for radio amateurs and shortwave listeners that encourages portable operation in mountainous areas. See . Basically "Activators" operating from mountain summits and "Chasers" both get credit towards awards.

Steptoe Butte rises about 1000 ft above the Palouse farm country. Located 50 miles south of Spokane, WA. it is within sight of Idaho. It is a state park with easy access to the summit.

As a SOTA activator I hiked the last feet to the summit and then set up my KX3 at the edge of the Steptoe Butte summit overlook. There are no trees on the summit so I strapped my 18' crappie pole to a rock pedestal, using it to support the high point of my 20 mtr end fed zepp.

I had posted to the SOTAwatch2 database an announcement of my intention to activate Steptoe Butte. My first CQ was picked up by the Reverse Beacon Network, compared to SOTA database and an activation spot automatically posted to the same SOTAwatch2 database. Instantly any SOTA chaster knew my frequency and operating status. I'm used to calling CQ for a while and getting one or, at most, two responses...suddenly it felt like I had a pileup to work, unfortunately I've no practice working pileups. In less than two hours I did work 15 stations in 9 states but I could have done better.

Notes to self for the next time:
- Copy directly to a log sheet rather than my QSO pad
- Avoid using my cellphone clock requiring me to punch it to get the current time
- Narrow selectivity first
- Use RIT to tune through the pileup for calls

and, a related safety item:
- If the antenna is within easy reach of curious public, hang a "Do Not Touch" note on it.

Hopefully next time I won't leave so many chasers without a QSO.

Sunday, June 16, 2013

Another way hang a C-Pole

When winter turns into summer I usually take down my 80 meter antenna and put it away. This year Beth was flexible enough to let me leave the mast in place and hang my 20 mtr C-Pole from it.

So far it has worked out well. I've only had this up for a couple of months but it's been through 16" of snow, record amount of rain, thunder storms, hasn't come down yet.

The mast is made from six sections of military surplus 4' fiberglass poles. These are the ones made to support camouflage netting and have a reinforcing ring at one end. They fit together pretty tight. There's no need to bolt sections together.

I just run the C-Pole antenna top spreader up the pole like a flag. It sways a little in the wind but does not twist around enough to be a problem

The bottom spreader is hooked to the top of the balun ( ) . The balun is captured by the conduit hanger it sits on top of.

The antenna is mounted approximately 16' from the house and only a few inches from the deck railing but at QRP power levels has not been a problem.

I didn't use any guys, just a clamp to the deck railing approx 10' off the ground and a hinged clamp staked in to the ground. (The radials in the photo are left over from an earlier antenna project and just left there.)

Sunday, April 21, 2013

It's not quite Spring in Minnesota

Last week Beth had an all day conference scheduled in the cities. I had the day free so this sounded like a great opportunity for some QRP in a different park.

Plans are made to be changed. The night before Beth's conference we got over 6" of snow and the temperature was forecast to be in the mid 30s. In the past I have participated in the FYBO QSO party but I wasn't planning on it this year. Where might I operate my KX3 from while staying warm and dry?

Eventually I thought of the Pavek Museum of Broadcasting. Located in St Louis Park, just west of
downtown Minneapolis, it is home to a great collection of antique radio, television and broadcasting equipment. It also includes a ham radio club, W0OEP, built around two Collins stations. On Friday I was more interested in the beam outside.

Steve Raymer, the museum curator, helped me get my KX3 plugged into the club yagi and I was on the air, warm and dry: a good combination for a cold snowy day in Minnesota. 20 mtr CW QSOs included VE3OF in Ontario and KK4BOB in Florida. Operating time was interrupted a couple of time, once while Steve demonstrated the museum spark transmitter and the other for a museum guided tour.

Sunday, April 14, 2013

Spring and QRP in the Park

Unfortunately spring hasn't yet arrived in SE Minnesota. It has, though, in central Texas. A couple of weeks ago Beth and I were down in Austin, TX visiting friends. My KX3 bag has a designated spot in the car. I rarely leave town without it.

During the week in Austin I enjoyed QRP QSOs with KA3J, W8WL/0, WA9FZP, KC2ZBZ and KI4TS. The most interesting QSOs, though, were the eyeball ones. On April 1 an old friend Dick, W5TA, stopped by for a visit while I was spending a few free hours in a Pflugerville city park.
On April 5 Beth and I took a trip down to Bastrop State Park. Unfortunately, in September 2011, 96% of the park was burned.  Only around 100 acres were saved. The rest is still blackened tree trunks. While set up and operating from one of the overlooks Jerome and his family came through on a hike and stopped for a rest and a snack. His young son wondered what was going on at the next table. Introductions led to a nice conversation about ham radio and a demonstration of morse code.

Monday, January 21, 2013

AWA LC CW Contest

Last week was the AWA Linc Cundall Memorial CW Contest. I used my 1934 style crystal controlled oscillator-buffer (47 to two 46s in parallel)  driving two TZ-20s in push-pull. The receiver was a 1936 vintage HRO Sr.

QSOs included W0CWU (MN), K1TG (CT), VE3AWA (ONT), N0EK (ND), WA9WFA (MN) and WB8APR (MI). Unfortunately, as I wrapped up with WB8APR, my transmitter output dropped to zero. Earlier I had had a hint of trouble when two stations reported chirp on my signal. I was keying the buffer stage, not the oscillator. Any chirp should have been slight. Contest or no contest the transmitter wasn't getting better by itself. After a few minutes of tube swapping and coil reseating I knew I wouldn't be back on any time soon. Eventually I found the problem: a bad solder connection. A little heat and solder fixed it. I had a working transmitter but I couldn't turn back the clock. The contest ended without my making any more contacts.

The HRO Sr and a three stage crystal controlled transmitter does make a nice late 30's CW station, though. It is one of my favorite winter operating positions. I'll be on it a lot. After all it is below zero today, I'm certainly not heading to the park.