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One of my favorite QRP groups is the 4 States QRP Group that sponsors Ozarkcon. Today we had an interesting thread going on their email list concerning slingshot antenna launcher and visibility of the line and sinker.

I’ve been working on that issue for a bit and offered my current solution. Still not 100% perfected, but it is working well now. Here in Florida, the tallest trees are mostly pines and the bark is pretty sticky with sap and lots of crooks and crannies that don’t allow monofilament fishing line to slide as freely as I’d like. I’ve tried the archery reel and slick braided line and although it does slide nicely through the trees, it is much slower and challenging to reel in and also is very prone to tangles and wind knotting which wastes time to untangle. In low wind or super sticky pine trees it is still the best solution.

Below are some photos of my cheapo solution to the slingshot line launcher. A $4 slingshot from Harbor Freight and a 99 cent shelf bracket from Lowe’s are the basic components. One challenge is being able to see where the sinker and line end up after the shot. I tried painting the sinkers, but in tall grass or lots of leafy trees, it did not show up as easily as I would like. The simple solution I found was to use fluorescent plastic surveyor’s tape (also from Lowe’s) to add both vivid color and some motion to help me locate the sinker whether in the trees, air or ground. I’ve also recently switched to red colored monofilament line called Cajun Red Lightning that offers a bit more visibility than clear monofilament.

Here are the basic elements… slingshot, Shelf bracket, spincast reel

If you are looking for an inexpensive simple solution, this might be the answer! Give it a try and let us know how it works for you. Leave a comment or better yet, join the 4 States QRP Group and join the conversation.

Closeup of the mounting of the reel

The assembled launcher — slingshot taped to bracket

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!

'The Bay' minimalist transceiver (without component values)

Back in March I wrote about my experiments with a minimalist transceiver design that was published in Sprat earlier this year.  Today I received an e-mail from Claude, W5FYI, who enquired about this work.  He wrote:

I, too, am interested in building G0EBP’s FET transceiver. One thing that puzzles me is reference in the Sprat article to the 560pF C5. Tony says it is for the final filter. Is he referring to the FET’s capacitance, or his value for the pi filter’s capacitors.

When you get your schematic ready, please let me know.

I thought I would share my reply as others may be interested:

Thanks for the e-mail.

Yes I wondered about that reference to C5 too.  I presumed it was the 100nF cap connected to the drain and the inductor on one side and the filter on the other.

I have done quite a few mods to this circuit and still tinkering trying to get a 700Hz  freq. offset on transmit, so avoiding issues if someone is zero beat.  My first attempts were poor, using an idea in Solid State Design for the Radio Amateur, which plays with some feedback in the oscillator circuit (Fig 6 p36 if you have that book).  I see a brief freq. shift and then it seems from my freq. counter the oscillator locks back again. Perhaps I need to switch in the capacitance with the crystal which I think will work better.  Been too busy recently with work to finish this experimentation.

Back to my main changes that I did.

1.  I changed the oscillator to a FET based Colpitts with a J310.  Better waveform, but lower output than a 2n2222 and hence only about 1/4W out with 9V.
2.  I have used a different muting process.  On keydown I put +Vsupply to pin 7 of the LM386.  That mutes the audio op-amp. See LA3ZA, Sverre’s notes on this at http://www.qslnet.de/member/la3za/Pixie_mute.htm
3.  Rather than have the key in line with the supply I included another transistor (PNP BJT) so key is connected to ground for transmit.  This helps if you mount an un-isolated socket for the key jack in a metal chassis.

I need to finish off the experimenting with the offset and then write up the changes for SPRAT.

I looked in my notes and see I blocked out the basic circuit but have not added any component values, so I attach it here, to help you.  The offset circuitry is not included.  I think you will be able to work out the component values from the original diagram.  If you need the calculated values for the Colpitt’s oscillator, let me know and I can supply those.

Hope the above helps you.

By the way I have started to call this transceiver “The Bay” after Morecambe Bay where G0EBP lives and coincidentally where I was born and grew-up.

The draft circuit diagram is above.  It is unfinished but still gives a good idea of what I have done with Tony’s, G0EBP circuit.

When I get time to return to this circuit I will report findings and updates here on the blog.

My favorite QRP group is the Polar Bear QRP gang! We have a good time and enjoy outdoors activities and trying to connect with one another at least once a month with some kind of activity. To escape some of the heat, I got an early start on the day. I wanted to try out a new mini-bac antenna configuration and knew it would take some time to get it up into the trees. BOY WAS THAT AN UNDERSTATEMENT! It was 110 ft doublet with a 40 ft feedline that was setup as a ladder line. Not an easy one to get up single-handed. Thanks to some tall trees, was able to get it up about 40-45 feet in the pine trees. It loaded great on 40m, but was disappointing on 20m so I ended up setting up my W3EDP in an L from my 20 ft Jackite pole to a nearby cedar tree at about 35 feet.  The sun chased me into the treeline where I settled in to chase bears.

Abandoned mini-back doublet feedline hangs in foreground

My xyl Connie took a picture that shows the mini-back feedline hanging in the breeze after I shifted positions and setup the W3EDP in the shade. Grrrrr!

Osprey perched right above my head…cell phone picture

Was able to work a couple of the Polar Bears, Mike W3MC in MD and Guy N7UN up in the mountains on a trail(?) in NJ. I heard VA2SG but he was at ESP level briefly then faded away. I did hear a few others working him though. WA8REI was working Guy but I could not hear him at all and ended up tail ending their QSO to connect with N7UN.

Got to work a few others through the QSB and poor signal strength on 20m including Pastor Les, K4NK in SC, KE5SBZ, Ed in TX, N1FJ in MA, and Phil W3HZZ in Atlanta so it was a nice way to spend a few hours outdoors in the heat.

Connie brought me a picnic lunch and we enjoyed the osprey and bald eagle show as they fished Lake Fredrica.

Had to drink extra coffee to copy speedy W3MC's signal

This is the life… outdoors and ham radio…making QSO's…PTL!

I bought a copy of Practical Wireless today and noticed the following in the Waters and Stanton ad inside the front page.

It isn’t often words fail me, but three hundred quid delivered for a hand held QRP antenna?!? I guess it would perform about as well as my home-made Wonder Loop.

Many work responsibilities have kept me off the air more than I’d like lately.

But we did manage to break away for a few days with family in Tennessee over Memorial Day. It was great to have an opportunity to get together with Chuck, AF4O the Hillybilly Bear and fellow Polar Bear QRP group member. We had an opportunity to work a bit of QRP portable in the Chickasaw State Forest in West Tennessee. It is a very natural and beautiful location and Chuck took me to his special spot in a very old and interesting cemetary set deep in the very tall hickory tree forest. Wow! I believe the latest date on the grave markers was 1927 and there were many from the early and mid 1800′s. It is a lovely and isolated spot.

K4UPG running a 30m EFHW sloper from the edge of the forest cemetary

Chuck said to bring along a screen shelter and I sure was glad I did! This was also a great spot for deer flies, hornets and other interesting biting bugs!

He had a nice setup and was running a random wire on 20m which he launched by throwing an antique glass insulator from an old telephone pole over a tree branch. He has a better arm than I do… think that heavy insulator would have broken my arm!

Back at the in-laws home in Jackson, I had some time to operate deck portable and was ably assisted by my niece Chloe. Conditions were horrible, but it was fun to be outside and hearing some sweet dits and dahs for a bit.

Now I am gearing up for the next outing of the Central Florida QRP group. The weather is HOT and the summer thunderstorms are back, but life and radio must go on… cu on the air!

72,

K4UPG

AF40 downs a Mountain Dew and doesn't miss a character of CW

Chloe gives me advice on copying cw through the QRN