Monday, June 14, 2021

ARRL VHF Contest Fun

 

I had such a great time participating in the ARRL VHF Contest this past Saturday and Sunday. As was my habit, I headed out to Hogback Mountain on the Skyline Drive. Hogback Mountain stands at a little over 3000 feet and has a good view of New England to the N/NE and Pennsylvania to the N/SW:
Hogback Mountain, FM08



My approach to this contest is laid back. In fact, the June VHF Contest is the only contest series that I participate in. (There is also a September and January segment. September starts to get in the way of hunting and, well, January is pretty cold on a mountaintop.) Since I'm casual about this, I really only use one Yagi and the FM vertical on my Jeep. Also new this year was a significant amount of QRM from neighboring operators. We'd step on each other every time we were operating the same band. We then decided that we'd not call CQ and hunt/pounce instead. Hunt/pounce worked, but it did reduce log entries.
Spring on the Skyline Drive

The Shenandoah Valley, Virginia



Equipment. My equipment was a little different this year. I blew out my IC-7000 to years ago; I replaced the same with an Elecraft KX3 using a Dual Band VHF/UHF Transverter made by
UR3LMZ
. All my SSB contacts were at 8W. (Note: next time I'll reduce power further to 5W and go for the QRP category.) I also used my vehicle mounted Kenwood TM-D710GA for most of my early FM VHF contacts. I then used the KX3 for both VHF and SSB. I know, I know: my Yagi is clearly horizontally polarized. Still, I made plenty of FM contacts with little degradation of signal. Besides, the FM contacts were local.
Elecraft KX3 with Upverter
My setup on Hogback. Flagpole holder, MFJ-1910 mast...and cooler.

    • Challenges/Observations.
      • I heard very little CW on the bands. I heard none--zip, zero--on the designated frequencies of 144.000-144.100 and only scant QSOs in the 144.200-144.300 range. I only made  two or three CW QSOs myself. 
      • Once I started operating primarily from the KX3, I found that moving between bands/freq tiresome. Next time I'll add the following to memory before going to the field and make sure I know the procedure for doing so in the field:
        • 144.100 (2M CW Calling/start of band)
        • 144.200 (SSB 2M Calling Freq)
        • 146.520 (2M Simplex Calling Freq)
        • 420 (70cm CW Calling/start of band)
        • 432.10 (SSB 70cm Calling Freq)
        • 446.00 (70cm Simplex Calling Frequency)
    • Future Plans/Expansion
      • I normally operate as a limited Rover. This means that I must transmit and make contacts from more than one grid. I normally spend all afternoon on the first day of the contest on Hogback Mountain. I leave soon after dark so that I can see the sunset:

    Sunset from Hogback

    Illuminated Clouds from Hogback

     
    On day two/Sunday, I go to Mass then normally park on the top deck of a parking garage in FM18 for a few calls to qualify. But this plan was impossible this year. The amount of RF pollution and new buildings invalidated this plan. I made a few contacts on FM, but that was it. For future contests, I will forgo parking garages and go a little farther to either Bull Run Mountain or Mount Weather. 

      •  If I feel ambitious, I may add a 430 MHz Yagi similar to my 2M Yagi. I can stack the two on the same fiberglass mast and use a switch to go between the two.  I also have a 6M Moxon that I built that I could press into service, but this might need it's own mast. It also doesn't breakdown so easy for the back of the jeep.

    Nice photo, but made zero QSOs on SSB with KX3 and Yagi. Made two QSOs on FM using Kenwood
    TM-D710GA mounted in my Jeep. Remainder of the QSOs made from my home.

    • Results. At the end of the day, I made 55 QSOs from FM08 and FM18. All but four QSOs were from Hogback Mountain. Best QSO: W1VD, Burlington, CT (363 mi) on 8 watts USB. A personal best. Hogback Mountain (elev. 3000') sure helps.

    QSO Map


    Saturday, June 5, 2021

    Get Ready, Get Set....

    The ARRL VHF/UHF Contest is next weekend. I'm reading my equipment in between chores. Crimped some shorter LMR-400 Max (started with 2', down to probably 19' now that I screwed up a section). I'll probably operate as a "rover." Like the last few years, I'll spend a majority of my time in FM08 on the top of Hogback Mountain along the beautiful Skyline Drive. Nothing like pulling an all-nighter hammering out some Morse Code like the fate of the free world rests with me and my trembling fingers. I'll follow up the next day from home after Mass (grid FM18) to fully qualify as a rover.

    Since I fried my IC-7000 last year, I'll be operating FM using my Kenwood TM-D710G in my Jeep. It will beacon my position via APRS. New this year: I will operate a VHF/UHF using transverter on my Elecraft KX3 by Alex Shatun (UR3LMZ). Will also have a small VHF Yagi with me as well. This should be plenty fun.
    Newly crimped LMR-400 Ultra


    Tuesday, May 25, 2021

    Parts!

    While I'm making judicious use of my junk box for parts--parts salvaged from garbage picking old TVs and stereos years ago--I still am short some basic components for my basic builds...mostly QRPp transmitters.

    Bill Maera (N2CQR) of Solder Smoke Podcast fame to the rescue! While I have many of these parts from various grab bags, there are some more unique items that will require a trip over the the Mouser, All Electronics, Jameco, or Digikey website:

    Transistors

    • 2N2222 (have a ton of these and 2N3904s from previous grab bags)
    • 2N3904
    • 2N3906 
    • J-310 
    • MPF102 
    • IRF510
    • [2N3053] (for the 10 Minute Transmitter)
    Toroids. (Funny story. I bought several T37-2 and T-37-6 through Kits and Parts, but I really didn't know until reading the winding data that I needed just a few more of different sizes and composition.)
    • 25 x T50-6
    • 25 x T50-2
    • 25 x T37-43

    Capacitors
    • Large supply of .01 uF capacitors (bypass)
    Resistors. I have a considerable grab bag that I still need to organize. I haven't been unable to fill my needs yet. Still, Drew (N7DA)'s picking at the Solder Smoke Daily News are helpful.

    Zeners
    • 8V

    Miscellaneous

    • Looking through an older book called W1FP QRP notebook, the author indicates that an aspiring builder ought to have some miniature ferrite beads to place on the base of the amplifier transistor to prevent VHF oscillation and VHF harmonics. 
    • I want to add a little more flexibility to my building methods. I've been using these 3x3" squares of perfboard that I found in my junk box, but I want to spread out my circuits more. I'll probably never approach the work of the Manhattan Build Master, Dave Richards (AA7EE), I ought to give it a go. This requires some supply of copper clad board. The boards in my junk box shattered when i tried to cut them to a reasonable size. Bill suggested I follow Pete's advice and buy CEM 1 boards on eBay. CEM1 is low-cost, flame-retardant, cellulose-paper-based laminate with only one layer of woven glass fabric.

    Ordnung macht SpaƟ

    While I've only built a few small circuits thus far, I found myself expending a lot of time trying to see what I have in stock for the next build. It became obvious that I would end up spending significant time hunting for parts in a box labeled "resistors" or "capacitors"--time that should be devoted to building, experimenting, and enjoying the fumes of some 60/40 solder. While it took the better part of an afternoon, here's the fruits of my labor. A significant time saver. 

    And while addressing some of the bulk part items, I suggest readers check out Drew's (N7DA) lessons learned over at the SolderSmoke podcast.





     

    Wednesday, May 19, 2021

    First QSO with the Ten Minute Transmitter

    At the recommendation of Bill Maera (N2CQR), I used the SKCC scheduling page to get someone to meet me on frequency for a QSO. Wish I had a video, but here's the log entry:

    K8JD (Commerce, MI)
    Bearing: 312°, 711km/442mi
    SKCC Nr 1395
    7.1228 MHz
    19 May 2021
    2330-2334 UTC
    Sent: 559
    Recd: 529

    Lots of adjacent phone conversations on LSB, but not bad at all for little 360 mW wonder....

    Saturday, May 15, 2021

    Ten Minute Transmitter On The Air with a Homebrew Antenna Switch

    Why I need This

    My Ten Minute Transmitter is just that--a transmitter. It is not a receiver. To get on the air, I have to:
    • Connect to a suitable antenna
    • Listen to any reply using a receiver or transceiver
    Since I have few choices of antennas, my transmitter will need to share the same antenna as my receiver. (In this case, my receiver is a KX3). And to use the same antenna, I need a switch that opens the connection to my 40M antenna when I'm transmitting, then close the connection to the transmitter and open the connection between the 40M antenna and my receiver. 

    Resources

    An antenna switch doesn't sound that complicated. I wondered if I'd need to connect all the negative/shielding together. I used the following resources:

    Information about capacitive voltage dividers are here https://www.basictables.com/electronics/capacitor/capacitive-voltage-divider In essence, I don't require a voltage divider since I'm not attempting to take readings through a scope.

    The Build

    I basically drilled holes on three sides of an Altoids tin for four very old BNC adapters that I scrounged from the garbage about 10 years ago. A SPST switch completed the fourth side. I used a short length of RG-8x coax to tie the hot terminals together. here's a picture:


    The Result

    The switch worked quite nicely after I remembered to use it! I called CQ several times. While nobody returned my call, I was spotted by Bob Delinger (KD7YZ) on the Reverse Beacon Network. (Bob is in Greenup County, Kentucky (Grid EM88ll) which is about 305mi distant. I registered a 5dB signal--not too bad since I'm putting out only about 360 mW).





    Wednesday, May 12, 2021

    Low Pass Filter Construction



    Background

    Next step after building a functioning transmitter: clean up the signal. 

    Moving Forward

    To create a Low Pass Filter, I used information readily available at the G-QRP site. A good page is the A Short Guide to W3NQN Harmonic Filters for QRP Transmitter Output. - George Dobbs G3RJV. This is a good overview, but I found the older version that I think, well, would be an easier for the time being. A copy of George, G3RJV first paper can be found here: A Complete Do-It-Yourself Kit ....... with just a few simple calculations (George Dobbs G3RJV)

    Design & Build

    Here's the design:




    And here's my parts:

    • 3 x T37-6 (for L2, 4, 6) 
    • 2 x 220 pF and 47 pF capacitors. These will be in parallel for a 267pF cap substituting for the 270 pF caps for C1 & C7
    • 2 x 470 pF and 220 pF capacitors. These will be in parallel for a 690pF cap substituting for the 680 pF caps for C3 & C5

    Finished Product

    Here's what the final product looks like:

    Top Side

    Underneath

    Results/Performance

    I listened for oscillation at 2x (14.260 MHz), 3x (21.369 MHz), and 4x (28.492 MHz). I never really heard anything on 14.260, but certainly did on 21.369 and less so on 28.492. The following video shows the test on my receiver and scope plus a quick voltage calculation on the dummy load.



    Next Steps


    • Finalize capacitor value
    • Assemble into an enclosure. Add BNC antenna connector and 3.5mm jack for a straight key
    • Make some QSOs




    Monday, May 10, 2021

    Moving Forward with A 40M Transmitter

    The Idea

    In a desire to build something to get me on the air, I've taken a step back from the 80 MMM and have decided to move forward with a 40M transmitter. Bill Maera recommended aiming at the 10 Minute Transmitter.  Quite sure this was on Bill's mind when posting Ciprian's version.

    I decided to not build a low pass filter for my 80M MMM. My thinking: I'm a parts cheapskate and I really won't be using the 80M MMM to get on the air. Yeah, I wanted to see an improvement of the carrier wave on the oscilloscope, but I'll be doing this for 40M, right?

    I collected some parts, ordered a few too. Bill recommended trying any NPN transistor that I had in inventory, so I'll thought I'd mock up the transmitter using a 2N2222 or 2N3094. What's the worst that can happen? I mean, there is the word "smoke" in the Solder Smoke podcast name. 

    Here's the design(s) that I used:

    Original 10 Minute Transmitter by Steve (G4RAW)


     


    Walter (KA4KXX)'s version as seen in the Solder Smoke blog..





















    And here's my parts:

    • 100uH coil.*
    • .1uF capacitors (2)
    • 240 pF capacitor**
    • 7.123 MHz crystal
    • 22K resistor
    • 2N3053 transistor***

    * Using 37-43 toroid, that's about 16-17 turns as indicated in winding data found on Kits & Parts.

    **Walter (KA4KXX) has adjustment instructions on the Solder Smoke blogplease be advised that the way to tune the "240" pf series output capacitor is to first connect a 50 ohm dummy load to the transmitter and peak the RF Output Voltage. If there is no defined peak then temporarily use a variable capacitor with a wide range because your value may be much different than mine since you are using another transistor, circuit board layout, etc. Also, note that in my version I connected the transmitter to a multi-stage antenna tuner before attaching that to my end-fed antenna so my signal out of the antenna was probably very clean. 

    ***Other NPN transistors such as a 2n2222 or 2n3904 should also work.

    The Trouble

    I breadboarded the circuit and... Nothing. Like absolutely nothing. 

    Now, those who grew up in 70's and 80's remember the teen biopic The Breakfast Club. In that movie, the nerdy teen who found himself in Saturday detention reveals his biggest failure: he couldn't make a lamp in shop class. You know where this is going: I felt like that kid. The 10 Minute Transmitter That Took Two Days to Build. 

    No worries. I now like to think that I'm grown up and laugh at myself, my abilities (or lack thereof), and some of life's little foibles. Be that as it may, Bill relayed some troubleshooting hints:


      On this project you might need an antenna or an antenna substitute.  Just put a 50 ohm resistor from the variable cap antenna connection to ground.    Then try getting it going while fiddling with the variable cap setting. 
      It should work with 9V.   But maybe try a fresh battery.  
      To check the voltages -- keeping the key up, the voltage on the collector of the transistor should equal the voltage of your power source.  
      If you've let the transistor get too hot, try with a new transistor. 
      Make sure you have the leads right on the transistor,  It is usually E B C facing the flat part of the transistor,  It is easy to get them backwards. 
      I think Walter was talking about peak output voltage.  Don't worry about that for now -- you just want to get it oscillating.   
      Make sure your receiver is on LSB or SSB or CW (not on AM)  Tune around a bit as you fiddle with it. 
      Peter Parker did a video on this: https://www.youtube.com/watch?v=cPPi7uLGtgY
      Perhaps more useful is this: https://makerf.com/posts/ten-minute-transmitter

      Hang in there.  Let me know how it is going. 

      Of course, I didn't stick to one set of variables. I did several things--all or some of which may have made the difference:

      1. I moved to 12v power. Actually, I used 13.8v and powered through a plug so that I could use my normal rig power supply or LiPo battery from portable operation. Pinout reminder:
       

      2. Most importantly, perhaps, I ditched the breadboard. Chances are some small connection is broken or I failed to visualize a vertical connection. "Time to melt some solder," said Bill.

      3. Added a variable capacitor so that I could adjust peak output at some point.

      Here's what my project looks like:














      And We're In Business

      We're oscillating, folks:
      Project Description

      Successful Oscillation