Posts Tagged ‘Accessories’

I am a CPG

Spent my birthday participating (casually) in the Straight Key Century Club Weekend Sprint. My Lake Fredrica neighborhood site was where I set up my shelter and 3 antennas. I had a 40m dipole fed with twinlead up 40 ft and running E-W. An End Fed Halfwave for 20m was nearly vertical suspended by a nearby tree. A twinlead 44 ft doublet on my 20 ft Jackite with the ends at 16 feet was setup running N-S to give me a bit of a mini-smorgasbord of antenna choices. Since it was really sunny, I hooked up my ACME GC100 Solar Charger and VW Solar Panel.

Bands were decent with 40m quiet and some DX coming through early from Eu stations. Nice to hear that again. 20m came alive and was pretty much the go to band for the majority of the day. I did check 15m a couple times but did not hear much and no one replied to my CQ’s.

In the middle of a QSO, my Jackite pole decided to collapse but I was able to finish the QSO with one end of the dipole about 4 feet above the ground. hi hi

The highlight of the day was my last QSO with EA3NO, Lluis in Spain. As the special station for the sprint there was a lot of competition but Lluis hung in there with my weak signal and pulled me out of the crowd after a couple attempts. THANK YOU FOR THE BIRTHDAY PRESENT Lluis!

Still wondering what a CPG is? Contest Point Giver! I am a really casual contester. Really the only reason I participate is that contests offer a fairly good opportunity to make some QSO’s. When you are QRP you have to do a lot of listening, plus pounce and search, but serious contesters will dig out weak signals to make the QSO’s so it is fun. I enjoy giving out points and reading the mail on ops that are faster than my cw comfort zone. Good practice, eh?

Here’s some photos from the day. Enjoy!

72,

Kelly K4UPG PB #173 SKCC #5415

Duh: Learning Curve #3–Coke Choke Works!

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)

C Pole Plot

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

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!

T Time

Labor Day here in the USA! So a day to play for most of us. Depending on the weather I may get a bit more on air time, but I have a project lined up too.

Some time ago I purchased a Deluxe Tuner kit from Dan’s Small Parts and Kits aka a QRP Mini Tuner by Mark L. Meyer as described in a 73 magazine article. It is a nice little set of parts and a schematic for the price.

T tuner

QRP Mini Tuner Kit

So I’m thinking this holiday might be the time to build that little T tuner out and see if I can load up the downspout that runs down the side of my back porch. I’ll let you know how it works!

Hope the bands hold up. Tonight’s QRP-L has a message from N4QA about how nice 40m is sounding right now! Sure would be fun to have our bands back from the QRN and low sunspot streak of late!

K4AHO Jim’s Rockmite Mods

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.

RM intro pic

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…

RM and NEScaf

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

Rockmite Mode Closeup 1

RM Mod pic 4

Rockmite another closeup

The Inner Workings of the NEScaf and Rockmite

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

Cannot Get Enough QRP Portable

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.

PB QRP

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

Logging assistant

When you are out in the field, especially on a windy hilltop, logging the contacts you make can be a bit difficult. One hand holding the radio or microphone leaves only one hand free to hold down the log book and write in it. If you’re using a hand-held and standing up to get the maximum height gain, it’s even more awkward.

A few weeks ago I hit on the idea of using a personal digital voice recorder. Initial researches suggested that they were a bit expensive – many models sell for around £70 or more. But diligent searching on eBay revealed that it was possible to buy them for much less than this.

The one I got is an Olympus VN-100 Digital Voice Recorder and cost £15.99 including free postage. It was described as “refurbished to new condition by Olympus.” This might be an indicator of a product that tends to fail and has a high number of warranty returns. However, this particular one was indistinguishable from new, works fine and is simple to use. It isn’t the colour I’d have picked if I had a choice, but price and functionality were the principal considerations.

I don’t know what the differences are between the VN-100 and the more expensive models apart from colour, probably storage capacity. However this model has capacity for more than 13 hours of recording – more than adequate for my purposes.

I find the VN-100 easy to operate with the hand that isn’t holding the radio. You just press one button to start recording and another to stop. A bar meter shows the level of the audio input. You can either say the callsign, time and whatever else you are interested in logging, or just point the device at the radio and make an off-air recording. At home it could be a handy shack tool for recording unusual DX contacts.

The only problem I found is that the voice recorder is just as sensitive to wind noise as the microphone in the radio. More than once I have returned home to find a recording was unintelligible. However, mishaps like this can probably be avoided with practise.

I’m finding my digital voice recorder to be an indispensable companion on portable outings. It’s also handy for jotting down ideas for blog posts that occur whilst you’re out and about!

End Fed Tuner Success… sort of

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.

Test lashup of EFHW TunerWhen 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.

In the box details

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… :-)

The SWR Bridge I want to use

SWR bridge I want to use

Thanks for your wisdom and experience on this one.

72,
Kelly K4UPG


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