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
Various QRP related email reflectors and lists are full of chatter about the Flight Of the BumbleBees (FOBB). Comments about the CW being too fast and the weather being too hot at this time of year make it sound like a broken event. IMHO it is far from being broken! It is probably the premier QRP event of the year. And I say, if it ain’t broke… yep, you guessed it, don’t fix it.
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.
Kelly K4UPG BB #10
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!
On the road again… happy feet dance! K4UPG is loaded and ready for a good day by the lake operating the QRP To The Field event for 2010.
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.
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!
These last two Polar Bear adventure radio sprints in January and February was quite an experience operating QRP (5 watts or less) outside in the snow. I never thought I would never do anything like this in freezing weather. There I was knee deep in snow; with a wind chill around 15 degrees, under an open air shelter at Cobus Creek Park, located in the northwest corner of Elkhart County in January. I was invited by Bob, KB9IVA, who said it would be fun. So I got my portable gear and winter parka and headed out to the site. When I arrived Bob wasn’t there. I got out of the warm car and looked over the snow covered picnic table. The bright sun reflected off the stone on the side of the building helped warm things up a bit.
First one gets the warmest spot!
Then the sun disappeared and it became colder. The heated outhouse was open so I warmed up for a few minutes.
QRP in the parking lot!
It was too cold for me to set up outside so I operated in my mobile on 40 meters. Bob arrived in a snowmobile outfit with a bag full of tools, and his ICOM-703 and MP-1 portable all band vertical antenna.
The antenna would not tune properly so I ran 25 feet of RG-59U coax from my mobile antenna to the picnic table. Then the portable battery pack ran out of juice. So I took my emergency car starter battery and hay wired a connection to the ICOM-703 and we were back on the air. When it’s cold radios and batteries don’t work properly. Wires become stiff, batteries quickly discharge, and the straight key was difficult to use. Not to mention your exposed fingers feel frostbitten. I had forgotten my gloves but you couldn’t send CW with them on anyway.
Our vertical in the park!
Cold stiff hands on a very cold key! YIKES!
I was more prepared for the February sprint but didn’t count on blowing snow. Participating in this sprint was, Bob, WA9S Keith, and Steve KB9ZVJ and I Ni9Y. Keith arrived late and operated inside his Jeep. I Made a half-dozen contacts from Utah to Colorado to the East coast with my HB1-A 4 watt transceiver using a 50’ end-fed wire only 27 inches high. Then the wires snapped off my battery pack. So we quickly repaired the pack with a new connector and we were back in business again.
2 Cold QRP Guys operate in the Feb 2010 PBMME
Bob had his IC-703. His headphone band cracked in two in the cold. Bob’s straight key was almost brittle and hard to use with gloves on. Steve operated SSB with his Yaesu rig, powered by a riding mower battery, feeding a sloping 20 meter dipole about 5 feet high.
A snow proof antenna for 20m
Last man sending!
It was getting too cold for me so I packed up and left as the snow began to really come down. Steve saw me packing so he packed up and so did Bob. Keith stayed behind moving to the picnic table and made more contacts in a small blizzard. Then Park Ranger paid a surprise visit to find out what in the world was going on. The ranger was satisfied that we weren’t suspicious characters after Keith explained the situation. The ranger failed to notice Keith had wrapped his antenna rope around the door handle on women’s entrance to the outhouse. There was no way anyone could open that door. The ranger probably thought we were a bunch of nuts playing radio in the snow. It was fun and we probably will do it again next season. Only next time I will be more prepared for polar bear weather. Oh yes I forgot to say this was the POLAR BEAR MOONLIGHT MADNESS event. You can read all about on their website http://www.n3epa.org/Pages/PolarBear.htm. Polar Bears all over the country and in Europe participated in the madness. The final polar bear event was held March 20th but I took a pass on that one because all the snow is gone so it wouldn’t be as much fun operating in warm spring weather!!!
The MEN OF ADVENTURE will soon take off again. Barry, WD4MSM says “QRP To The Field” has just been announced for 2010. He recalled that we took part in the 2009 version that had as its theme “The Great Depression.” We operated from the WPA site of Monkey Island in Mishawaka (the bridge to Monkey Island was built by the WPA).
This looks as if it might be an ideal outing for us. Saturday, April 24, 2010 Spicer Lake Nature Preserve http://www.sjcparks.org/spicer.html Small picnic shelter available; Trees for antenna support if needed; Restrooms (heated and immaculate) just steps away; Ample parking for hundreds! Just minutes from South Bend; Plenty to do for family members and visitors (trails, grills, visitor center, two lakes, etc.); Handicap accessible trails and parking immediately next to the suggested operating position.
You to can join the MEN OF ADVENTURE even if you don’t have a QRP rig. Just show up to learn about portable operation and how to put up antennas where they don’t belong. Who knows maybe you to will be just as nuts as the other members of the group are? Present company accepted.
That’s it for this edition.
73’s Dan, email DAN
p.s. Consider operating the special event KØS Strange Antenna Challenge Special Event — May 29-31, 2010. Start Date & Time: Saturday, May 29, 2010, 1000Z End Date & Time: Monday, May 31, 2010 at midnight (local time zones) This is not a serious event. We are all out here for fun! K0S will employ out-of-the-ordinary antennas to promote Amateur Radio and making do with what might be available during an emergency. Individuals and clubs may participate as “satellite stations” by using anything but wire or pipe for a radiating element and adding “/K0S” to their call signs. Details are on the KØS, Strange Antenna Challenge Web site. Strange antennas used in past events, dating back to 2002, have included folding chairs, paint easels, ladders, tape measures, dog kennels, fences, cots and chicken fencing with a trampoline as a ground plane. “More people share in the fun each year,” says Erik Weaver, N0EW, a Strange Antenna Challenge founder. “I hope you give me a call this year with your very own strange antenna. Now let’s play radio!”
45F a bit of sun and a lot of wind! Today I escaped being selected for jury duty so opted to get the oil changed in my car! I called and my shop was not too busy and said, “come on down!” So I packed my 30m SST, BLT+ tuner and accessories and took off. Instead of sitting in the waiting area and reading out of date magazines and watching silly game shows, I walked out to the parking lot and threw some wire into a couple small trees. I only got the main 46 feet wire up about 15 feet on one end and sloped it through another small tree and out to my camping table. I ran a counterpoise of 23 feet to the same small tree and hooked up my trusty BLT+ tuner.
My Oil Change Parking Lot QTH for 30m
A quick tune found a couple week signals. I tuned the antenna a bit, called CQ with no luck, then heard a decent 579 signal calling CQ. Bill, NG3O in Columbia, MD replied and although I wasn’t strong (539) he thought he could copy me. He sure did a great job and we enjoyed a nice QSO for almost 30 minutes. Sure is pleasant to work a good fist without any QRM. He said I was his first Oil Change Parking Lot QSO.
A few minutes later, I connected with Rudy, W8RJW in Columbia, SC. He was a strong 589 and gave me a 559. We had a nice qso for several minutes too. It was a fun way to pass the time while I waited on my car maintenance to be done.
The band got pretty quiet afterwards and though I heard a few more stations, it was time to pull the plug, take down the wire and go home. I think I have figured out a new way to pass time when the opportunity is present. Hope you will give it a try too!
Today was Polar Bear Moonlight Madness Event! I wore my new Polar Bear hat and it brought me luck. I setup in the 3 story prayer tower at Pioneers, my ministry headquarters. That kept me out of the weather and got me up in the air a bit which helped my W3EDP antenna do its thing.
Pioneers Headquarters Prayer Tower on left
Bands were pretty good and there were a lot of QRP signals out there as well as SKCC and FIST ops. I worked a few of my fellow Polar Bears:
Then I worked a few non-PB’s and had some good QSO’s with SKCC members.
Next weekend is the FYBO and the Central FL QRP Group will be operating its first multi station- multi operator event at Sylvan Lake Park in Sanford, FL. If you’ll are down this way look us up. If not, give a listen for K4AHO which is the call sign we will be using.
Here’s to many good QSO’s. Thanks to all the good ops with good ears that heard my peanut whistle 2 watts today.
