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

I still think the tin foil does the magic!

After years of neglect, this analog era ham is willing to admit I only understand a bit about digital electronics. (Yep! Pun intended.) Well into the second week of my sabbatical leave, I have begun to plot out a course of study to get up to speed on the state of the art that I have so long neglected. Should be fun. There seems to be a good bit of open source help online these days and I have my trusty ARRL Handbook, Extra Class study guide, Antenna Handbook and assortment of other aids.

Any suggestions from the veteran techies out there will be greatly appreciated.

I am a learn by doing/hands-on sort of guy and find deep theory puts me into a semi-catatonic state after a few minutes.  For me, it’s a whole lot more fun to take a stab at things and find out if they smoke, and it also makes a lot more sense when I can dink and tweak and see what that actually does. But since that is a bit expensive, perhaps I should learn how to use software like spice to do simulations? Any recommendations for how to learn this software?

Another area of toe dipping will be learning to do antenna modeling. For years I’ve looked at those charts and made little sense out of them. HA… I like to throw wire out and see what happens, but in the summer heat, maybe it is wiser to do a bit of modeling from my air conditioned den?

Thanks WX7S-- Your site looks AWESOME for learning this stuff!

I’ll try to share some of the learning curve, but would love to hear from some of you that have gone before. Shortcuts are nice. WX7S your site looks like a great place for me to start! Thanks for the effort it takes to do that.

This weekend (Sat 14 Aug 2010) the Central Florida QRP Group will gather for breakfast at 0730 (Denny’s in Sanford, FL) and off to Sylvan Lake Park in Sanford, FL at 0900 EDT to operate. If you like cw and qrp or are just plain curious… come join us!

Sunday the bands were full of QRP ops, both home based and portable, so the activity really did make a BUZZ despite band conditions that have not been all that helpful to hf qrp contacts.  The weather was HOT, but hey, find some shade, altitude or water and go for it. Historically this is the time of year for this event and as others have commented, it keeps our activity up during the summer time when vacations and mowing the grass take their toll on ham radio activity.

As far as fast cw, I’m not fast (not even close hi hi), but it sure is fun listening to the buzz on the bands rather than QRN and a high noise level with only a few weak signals. Certainly I am not a hard core contester. My cw skills are still in need of practice, but isn’t that what events like this provide? I often have to listen multiple times to get the callsign and info but that repetition and practice pushes my speed and confidence level up every time I try. After listening to a fast op several times I have the info I need and then I jump in and have fun making a contact at speeds faster than my comfort zone. Most of us slow guys can send faster than we can receive, right? Come on in, the water is fine, and FUN!

My XYL, Connie and I drove over to Honeymoon Island State Park on the Gulf Coast in Dunedin, Florida. This is a very pretty beach, not overly crowded most of the time and has been one of the top rated beaches in the US for several years. The weather cooperated, there was no sign of the BP oil spill that has run so many tourists to other locations, and we snagged a primo spot to operate right next to the water.The only negative, if you call it that, was that the view was sometimes distracting, but sure was enjoyable.

K4UPG Distracting View from my FOBB 10 Site

K4UPG Honeymoon Island FOBB Site July 2010

My trusty Sierra and Buddistick provided plenty of action so I never switched over to my mini-bac Delta Loop backup antenna. I also stuck to 20m the whole contest since 40m has been in such poor condition here in Florida lately.

One of the great things about these events is the leveling of the playing field. It is fun to contact the guys that write the articles, create the websites and design the equipment that we use for our hobby. My score was modest at 26 QSO’s, 18 Bumblebees and 17 states and provinces but it was one fantastic day of activity for me! Being able to connect with the big guns of QRP was a thrill too!

W8DIZ Stops By to say Hello to K4UPG

K4UPG search and pounce FOBB 10

For me, one of the highlights was when W8DIZ rode over to meet me as I was setting up my site. Diz lives about 3.5 miles from Honeymoon island and is a regular bicycle visitor of this great beach location. I’ve been a customer of his toroid and kit business and have benefited from the info he has shared, not to mention being one of the movers and shakers of the Famous Flying Pigs QRP group. Diz I was honored that you took time out from a busy family day to swing by and say HI! Thanks for the help getting our screen house up too!

Thanks to Adventure Radio Society and the guys that put this event on for all of us. We appreciate the effort it takes and you deserve the very best of 73′s from all of us.

72,

Kelly K4UPG  BB #10

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!

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

K4UPG ready to roll to QRP TTF site

Loaded with ALL the options!

Then came the wind knots in the antenna launching rig! I wanted to get a doublet up as high as possible. Took nearly 2 hours to get my antennas up in the air. LESSON LEARNED: It is really helpful to have another person along to help untangle all the knots that wire and string seem to make all by themselves.  Getting  the antenna up quickly is a key to portable ops. Grrrrr!

One of several tangled messes that delayed the antenna deployment

LESSON TWO: After a delayed start, I spent a lot of time moving my portable table to keep out of the direct sun! With temperatures in the upper 80′s it was HOT and direct sun causes my Sierra to drift a bit which makes qso’s more difficult. Need to get a sun shade setup and not waste time moving my position.

The band conditions were pretty poor and I did not hear as many stations as I had hoped. The ones I did work were tough going and seemed like others could not hear me responding to their CQ’s.  I didn’t even hear a lot of Florida QSO party ops, but sounds like others that were farther away did. In 5 hrs I managed three whole qso’s with TTF stations. I did hear one Polar Bear– Martin operating as VA3OVQ but he could not hear me when I replied to his CQ.

Warning sign about 30 feet from my operating site!

It was fun to be outdoors and playing radio! I did not get eaten by our neighborhood gator either! Maybe next time out will be better contact-wise.

The main picnic area near the ferry landing

The team consisted of Wally Crew, KG4LAL, Jim Diggs, K4AHO and Kelly, K4UPG. We used the special event callsign K4T on operated on 20m cw and ssb, 30m cw and a few unsuccessful attempts at 40m & 15m cw. Jim was our secret weapon on 20m with his good cw, K-1 and a Par End Fed antenna in vertical configuration on a 33 ft MFJ telescoping mast. Without his contribution we would not have been successful! So a big thank you Jim for your good operating skills and equipment that made it happen in less than 8 hours at QRP levels.

FL481 is ready for future activations!

Thanks to the Polar Bear QRP group, QRP-L members, 4 States QRP Group, GORC,  QRP Spots, US Islands organization and HF Packers that helped out by listening and attempting to connect with our effort on Hontoon Island. It was fun to work as a team!

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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!

Tiny Loop goes into action

Bart AI4NF brought his new MFJ 936B Loop tuner and setup very quickly. It seems to hear very well and soon the sound of cw was in the air. 20m was pretty active and eventually a signal was even heard on 10m! What a blessing! We did learn that the antenna was coupling to the metal frame of the card table and made it difficult to tune. After putting it on the small cooler it tuned more normally, with a very sharp and obvious peak when in resonance. Later we put the cooler on top of the table and that solved most of the problem and eliminated some of the ground coupling and loss.

I got to test my clone of Nick WA5BDU’s End Fed Halfwave Matching Device. It worked great and I was able to tune sloping half wave antennas on 40 and 30 meters. This tuner is unique in that it is simply a toroid and does not use a capacitor at all! On the bench it tunes 3-12Mhz at 1:1-3 to 1 half wave antennas. Next outing I hope to test the 80m halfwave and see it theory and practice agree.

Great day to be out at the lake even if it was windy!

K4UPG on 30m lakeside in SE Orlando, FL