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Had a great time setting up the C Pole antenna in a tree suspended configuration. My good friend and cohort, Jim Diggs, K4AHO came by with his AIM 4170 Antenna Analyzer and we were ready to tune the antenna and get a feel for it.

LESSON: A good analyzer makes tuning an antenna fast, simple  and accurate! The AIM 4170 gave us a TON of info (most of it going over my head) and let us see how the C Pole was doing in several areas.  Take a look at this output! (Click on the image for a larger version)

K4UPG C Pole Scan Results

LESSON: I followed Niel’s directions, but did not have a small plastic coffee container so used a Quart Coke bottle instead. So I call it a Coke Choke and it seems to work well. Here’s a photo to show it off!

Coke Choke Ready for Duty

I think this one is a keeper. Goes up easily, hears well and loads nicely too. I made a few brief contacts and called it a day, but look forward to more C Pole action in the days ahead.

72,

Kelly K4UPG PB #173

p.s. Don’t forget to vote in the Ideal Ham Radio QTH poll on the blog!

Here’s an email from my good friend and cohort in the Central Florida QRP Group. Jim wanted to share his latest mods for the Rockmites and some thoughts on the NEScaf filter. I think you will enjoy his notes too …

Kelly,

I thought I would bring you up to date on my latest project. I just finished a Small Wonder 20+ and used it on the Flight of the Bumblebees. I found my earbuds a little weak on audio output and the IF bandwidth of the SW20+ a bit wide for my liking. I read the specifications on the NEScaf filter offered by the New England QRP group and decided that that would be the best solution to my problem and be usable on other radios as well. I ordered, built and installed the NEScaf board in a TenTec TG-24 enclosure. I tried it on the SW20 and it sounded like a viable solution.

The Rockmite and NEScaf filter in Ten Tec Enclosures

I also have a 40 Meter Rockmite in a TG-24 enclosure and decided I would see how well the RM/NEScaf combination sounded. The Rockmite, of course, uses a DC receiver and the bandwidth is determined by the upper response of your ears… My RM sounds like about 40 khz wide, hears the whole band for me as my response is in the upper tens of kHz. Yes, I know, at my age 69 it shouldn’t be but is. Been tested. At any rate suddenly the Rockmite bandwidth is manageable. I had some audio artifacts, whistles and the RM sidetone would drive the NEScaf into cutoff which only a power cycle would clear. I googled the problem and Charlie KE2SP advised lowering the NEScaf input Z with a 10 to 47 ohm input load. I installed a 27 ohm resistor on the input connector and suddenly all artifacts, whistles and sidetone problems disappeared. WOW, the RM is really sounding great! Except the RX/TX was very low. I measured it at 500 cycles and the NEScaf would not tune down that low…

Closer Look at the Finished Rockmite and NEScaf

After considering several approaches to the problem and considering that the RM crystals don’t oscillate on exactly the QRP frequencies, I settled on completely revamping the RX/TX method used in the RM. Using the RM40 as a test bed, I removed D5, D6, R9 and R10. I purchased 2 Murata trimmers( TZ03 Series) from Skycraft, our local Surplus emporium, and installed them in the holes for D6 and D5, R9 combination of holes. I had to cut a small run on the right side (antenna connector side) to isolate that pad from Vcc and jumper to two trimmers together… I also had to drill out the pads to accept the trimmer leads. The Fet Q2 does a great job in switching to second trimmer in and out for the offset. The alignment was not difficult but I recommend using a freq counter connected thru a times 10 scope probe to the physical top of R5 (base of Q5). Don’t have to key the Tx to see the freq… I set the trimmer in the D6 position for the higher freq (7.030750 Mhz) and the other trimmer for the lower frequency (7.030000 Mhz. The trimmers I use are available at Digikey. I used the Red colored model (4.2 to 20pf, N750) but the Blue colored (2.7 to 10pf, NPO) might have been a better choice. These guys are Digikey p/n 490-1971-ND and are $0.43 each… I also changed the RM40 volume control from an audio control (1 Megohm) to a RF front end attenuator control (1.5 kohm) and there is a noticeable improvement in the overload and broadcaster breakthru problem. I strongly recommend these changes. If you can build the RM you can certainly modify it… If you break it, build another… I plan to make the same modification to my RM80. (CLICK THE THUMBNAILS for larger view)

Rockmite Mode Closeup 1

Rockmite another closeup

The Inner Workings of the NEScaf and Rockmite

How did it work? Well, the RM/Nescaf stack is now a real radio not just a toy. I worked WD8MHT Raul in Waynesville, NC one morning this week and we had a great conversation. He was 569 to me and I was 439 to him. His TS570 was working hard but copied me no problem. The amazing thing for me was that there was a really strong signal at 700 cycles and Raul was about 200 cycles higher. I tuned the Nescaf center freq on Raul and sharpened the bandpass and turned up the volume and he was armchair copy the entire QSO… WOW, not a struggle… I have since used the NEScaf on my SW20+ and yes, it works great…

I have attached a couple of pictures of the stack and the innards of the RM for reference. The switch on the front is for a future expansion.

72

Jim

K4AHO

Now into the third week of my sabbatical, I am surprised how much I want to get out and operate my QRP portable gear. Guess I have deprived myself over the years of being a confirmed workaholic and avoiding time off, vacations, and time for my favorite hobby.

Grrrrr! The Polar Bears Are On The Loose!

This should be a good weekend for QRP portable. The Polar Bear QRP Group will be out for another Polar Bear Summer Picnic Event and Polar Bears from Spain to the West Coast of the US will be out looking for BSO’s. Grrrrr! I am PB #173 and we’re over 200 members now. With the new Twitter and APRS connections to QRPSPOTS.COM which also point to the excellent spotting site of K3UK with a section for FISTS/QRP Ops to spot and sked one another, there are plenty of ways to use technology to help find each other. Add in a few other contests and state QSO parties, and there should be some buzzing going on this weekend. Makes me wonder when the FOBB results will be announced! Buzzzz Buzzzzz

I’ll be out and if all goes well I will be field testing a new C Pole antenna based on the suggestion I received from Neil W0LVZ. I added some switchable capacitance to my BLT+ and have rewound the main toroid to see if I can push the range a bit more with it so will have a delta loop and probably my W3EDP in the air too. I love playing with antennas and am still amazed when the ones I build actually make contacts!

Give a listen for me on the QRP watering holes on 40m, 30m and 20m Saturday morning. I’ll be self spotting on QRPSPOTS and the K3UK sites to make it easier for you to find me. Let me know how my newest antenna is workin’.

72,

Kelly K4UPG

PB #173

Kenwood Corporation recently announced the October launch of the long-awaited TS-590 HF/6m transceiver. Described in some quarters as a “K3 killer”, the new transceiver uses the novel (for modern Japanese radios) approach of a single conversion receiver with a low (11.374MHz) IF on the amateur bands to give what is claimed to be exceptional dynamic range.

The news release bears careful reading, as what it doesn’t say is as interesting as what it does. The receiver will have a 6KHz roofing filter directly after the mixer, followed by a 500Hz or 2.7KHz filter (both included as standard) after the post-amplifier. But a footnote states that “For 1.8/3.5/7/14/21MHz amateur bands, when receiving in CW/FSK/SSB modes down conversion is selected automatically if the final passband is 2.7kHz or less” which suggests that a conventional (for the Japanese) up conversion will be used for the short wave bands, AM or FM modes, the WARC bands, 10 and 6m.

I think the current obsession with receiver performance figures is absurd. I am far from being a member of the Elecraft fan club, but even assuming the TS-590 does turn out to outperform the K3 on the main amateur bands, I think anyone considering swapping their K3 for the Kenwood on that basis would be foolish.

As far as I know, the Kenwood will not have an option for a second receiver, nor one for a panadapter. It will not have the transverter and external preamp interfacing (which I use to insert the MFJ noise canceller) nor an independent receive antenna input. I doubt that it will have fully isolated audio inputs for data nor a soft ALC in digital modes that allows you to vary the power output in PSK31 without fiddling with computer mixer settings to avoid IMD problems. I’m sure it won’t have an internal 144MHz option either.

Whenever I look at the features of the K3 that I am currently using, I realize that there is nothing else on the market at a price I am willing to pay, nor which would fit on my operating desk, that could do what my K3 is doing.

The price of the TS-590 will be 228,900 Yen, or about £2,000 by the time you have added on VAT (never mind the usual exorbitant UK dealer mark-up.) If it goes on sale here at £2,499 I will not be surprised. Compared to currently available HF radios and Kenwood’s previous HF models including the TS-570 to which this new rig bears a considerable similarity, the TS-590 looks overpriced for what in the end is nothing more than a compact HF/6m radio.

A K3 killer? I don’t think so!

Had a good day in the park with Jim K4AHO and Wally KG4LAL. Spent a good bit of time testing a couple tuners for End Fed Half Wave antennas using Jim’s AIM 4170. Wow is that thing a great tool for tweaking antennas! Info overload!

I built an antenna tuner based on AA5TB’s design for an end fed half wave antenna. I am using a 3 ft or so counterpoise on the ground as Steve suggests. On the analyzer in a test lashup it was a bit touchy to hand capacitance but tuned well even up to 21Mhz. Since I am not thinking of backpack size I used a pretty good sized enclosure for it. I am using an air variable 6-160pf cap instead of a polyvaricon like Steve used since space is not a big issue. I also used a T68-6 toroid instead of the T50-2 Steve used.

When I mounted it in a plastic box the sensitivity seemed to increase. I have not put a LED SWR bridge in the box yet, as I was waiting to see how it worked before adding more variables. Today I was able to put an AIM 4170 analyzer on it and it did tune the antenna… seems that the air variable I used is perhaps a tad small. It is almost fully meshed on 40m cw and on 20m it acts like even at minimum capacitance the sweet spot is very narrow and hard to tune.

Here's the innards

My question(s) are:
1) Is the hand/body capacitance normal? If not, what might cause it to
be so touchy?
2) Would my parts layout be part of the issue?
3) Does the DPDT switch (mini toggle) I added for later use with the SWR
bridge add significant capacitance to the circuit? I was able to match a
21Mhz load on the raw test setup, but not once it is in the box.
4) I have a small bus wire for a ground, do I need to increase that?
5) Is the plastic box the problem? Would it be better in a metal enclosure?
6) Am I asking too many questions? Sorry, this is how I learn. Build,
test, ask…

SWR bridge I want to use

Thanks for your wisdom and experience on this one.

72,
Kelly K4UPG

As one of the many antenna restricted condo owners of America, I cannot operate as often as I’d like. The hassle of putting up and taking down temporary antennas wastes time, isn’t always practical and generally spoils the fun for us.

Great that we have some holidays and time off as it allows a bit more opportunity to get on the air. The MI QRP group hosted a 4th of July Sprint and although the hour was late (7-11PM EDT) since I did not have to go to work Monday, I took advantage of the chance to work a few of my fellow QRP ops.

Rain and lightning welcomed my efforts to set up an antenna. So I forsook my normal setup and settled for a twinlead 44 foot doublet hung from my 20 foot Jackite pole which was bungee cord strapped to a ladder in the back yard of our condo. The antenna ran north south so much less than ideal, but at least I could get on the air.

Freshly Built NEScaf saved my bacon!

The day was saved by my freshly built NEScaf filter. As one of the lucky ones, I recently received the latest edition of this great kit provided by the NE QRP bunch. It enabled me to listen to cw despite the high QRN and background hash from neighbor’s TV’s, computers and air conditioners. What a joy it is to actually hear stations through the noise. This is a must have accessory for the condo based QRP op! I am still learning to use it well, but am mega-impressed with the capabilities it offers. With this audio filter, I could null out the QRN and peak the CW signals making for much more relaxed and enjoyable copy. The extra audio boost helps my little Sierra audio too. Keep watching for the next round of kits!

Look out Hontoon Island the Polar Bear of Florida is coming your way! Good Friday, 2 April 2010 Polar Bear QRP member #173 (aka K4UPG) will attempt to qualify Hontoon Island as a US Island on the Air by making 25 contacts including at least 2 DXCC entities.

Hontoon Island is a beautiful place for some QRP Portable Ops

Activity will start about 1400Z after the ferry ride over to the island. Plan is to use special callsign K4T for recognition.

Look for us on 30m cw (10.106-10.116 MHz) and 20m cw 14.050-14.070 MHz and on the hour we will check 15m 21.060-21.070. If anyone shows up to assist, will also attempt ssb on 14.250-14.260 MHz island corridor. All ops will be QRP so we’ll need your help to pull us out!

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Fishing is good!

If things go well, our Central Florida QRP group may consider this as a new operating site! If you are in the area, come on and check it out with us.

Hontoon Island closes when the sun goes down!

Thanks to Florida State Parks for the fine pictures!

P.S. We did it 4.2.2010!  Over 30 QSO’s update coming! I am TIRED!