AmateurRadio.com

If you plan to become active on Canada's new 630m ham band, one of the first things you're probably thinking about is an antenna and how to make it resonant. Without the proper instruments, determining antenna resonance below the broadcast band can sometimes require a combination of good luck and black magic!

One of the most useful pieces of gear for me has been a simple 'antenna meter' designed by Lyle Koehler, KØLR, who was very active at one time on the 185KHz 'lowfer' band. Although the original circuit was designed to cover a lower frequency range, it can easily be modified to cover the 2200m and 630m bands.

The KØLR LF Transmitter

The device is actually a low power (~1/2w) VFO-controlled transmitter designed to look into a 50 ohm antenna system. Since most LF antennas are matched to 50 ohms, either through a separate matching transformer or by tapping up from the bottom of the antenna's loading coil, the 50 ohm feedline from the antenna system is simply connected to the antenna meter's output and the VFO tuned for maximum deflection of the meter. The resonant frequency is then directly read from the calibrated scale of the antenna meter's dial. With most backyard LF antennas having a very narrow bandwidth along with a high-Q, the meter peak is quite sharp and easy to find. Look for a peak meter reading between 50-70ma as you sweep the VFO across the antenna. Normal current values will be very low until resonance is hit.

KØLR's original article gives more details and can be found here.

The 470pf capacitor (C in my diagram) determines the basic frequency range. To modify the circuit for dual range (both 2200m and 630m), I added a SPDT switch at pin 1 of the IC so that I could switch the value of "C". For coverage down to and below 136KHz, I used ~ 725pf (a 680pf + 47pf in parallel) while high end coverage up past 500KHz required just 250pf (220pf + 27pf in parallel). These values should get you very close to the required ranges and once installed it is an easy task to calibrate the tuning scale by listening to the signal on a receiver or measuring it with a frequency counter. I also chose to install the 1M 'modulation' resistor that gives the signal a distinctive FSK note.

The meter will quickly tell you if your antenna is too high in frequency (capacitive) or if it is too low (inductive) so that the proper corrective measures may be taken to resonate it within the 630m band. Once resonant, attention can then be paid to bringing the impedance match as close as possible to 50 ohms and a 1:1 match. Depending on your method of impedance matching, there may be some interaction between tuning for resonance and impedance matching but a perfectly resonant 50 ohm system can be achieved with a little juggling.

Although not updated for several years, KØLR's website contains much good information regarding simple backyard LF antenna systems (both transmitting and receiving), preamps and weak signal receiving techniques. It is well worth a close look if you are designing a new 630m station.
Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

I am writing this from Zurich. This is the first of 11 days in Europe, a trip has a heavy radio theme. Tomorrow the Ham Fair in Friedrichshafen get's kicked of and I will be there. This will be my first trip to Europe's largest amateur radio event. I am excited about meeting some friends I've never met.

Next weekend is the 50th Anniversary of the IOTA Program. A celebration and conference will be held at the Beaumont Estates in Windsor, near London. I have participated in IOTA for over 20 years and will see a lot of old friends there.

I also want to activate a few summits as time allows, which brings me today's highlight. Even though I am jet lagged, I managed to activate Altberg, HB/ZH-015, which is worth 1 point. This summit has been activated 613 time counting my activation today. When I saw that, I thought this must be a drive up and an easy one at that. While this is not a difficult summit, it does require a 2 mile +/- roundtrip and 300 feet elevation gain. Very nice trail and a nice walk.

We had an interesting encounter with three elderly guys on the trail. None of them spoke a word of English and the only German I know it Guten Tag and no spreichten Duetsche. So imagine me trying to explain what I was doing on their mountain. I did finally get the concept across that I was a ham. I'll mispell this but is something like amateurfunk. We had all heard that word. The next obstacle was to explain my morse key. The term "morse code' met with blank stares, but when I said, "you know dit dit a di di dit". Ah, "morse' ya. They were having as much fun with it as I was.

My XYL, but with her camera, so we can't download them to iPads, but I did take a picture of my travel right. An MTR, 13' telescoping pole, 9V battery, ear buds and a micro key. I managed 12 QSO's and activated my first EU summit and my first HB9 summit.

I can't figure out how to get a picture from my iPad to the blog, so pictures will have to wait untill later.

I will try to post regularly during my trip.


Mike Crownover, AD5A, is a regular contributor to AmateurRadio.com and writes from Texas, USA. Contact him at [email protected].

in South Plainfield!

Field Day is two days away and the weather here is supposed to be gorgeous! Psyched!

72 de Larry W2LJ
QRP – When you care to send the very least!

Larry Makoski, W2LJ, is a regular contributor to AmateurRadio.com and writes from New Jersey, USA. Contact him at [email protected].

G1KQH has told me that the 9-band multmode transceiver, the X108 from China, can now be ordered on-line.

http://www.wouxun.us/item.php?item_id=346&category_id=65

Personally, I’d prefer the FT817 but, even with shipping to the UK, taxes and duty , the price is attractive, even if the product looks rather ugly (to me). It still looks “back shed” design to me. Personally I’d rather wait until the Chinese are really there with their designs. Others may disagree, but the industrial design of this product certainly lets it down.

Also, this is a kit, but with very little soldering.

Roger Lapthorn, G3XBM, is a regular contributor to AmateurRadio.com and writes from Cambridge, England.

After living here in the new house since January, I haven’t had a lot of chances to use the radios, even though I now have a room for my hobby (shared, of course with KD2CHE’s sewing).  The shack has been piled with things to sort through, requiring some digging and re-arranging to get to the Atlas 210X.  A few days ago, I finally went through the pile and did some major organizing.  I now have a nice work surface, and all of the radios set up and working (including a recent flea-market find, a snazzy FRG-7).  Tonight after tuning around on 20 meters I answered a couple of calls.  The second call was from 9K2UU in Kuwait.  This contact is now my second-best distance since I got my license (about 6800 miles), and the best from home (the no 1 was Namibia from my 10 meter mobile here at the beach).  Barrak gave me a 5-7, and he got a 5-9 from me.  All of this with an old Atlas 210X, and a 35 foot end-fed sloper into a 9:1 UnUn.  I’m happy with that.

Neil Goldstein, W2NDG, is a regular contributor to AmateurRadio.com and writes from New York, USA. Contact him at [email protected].

From Jeff, N2LXM:

On Friday June 20th, 2014 at 18:45 Zulu radio communications was established on 7.150 Mhz Upper sideband between the Marconi Wireless, Wellfleet station site in Cape Cod Massachusetts and the Marconi Wireless, Belmar Receiving Station, Wall Township New Jersey. Amateur Radio Station KM1CC had as a guest operator Princess Elettra Marconi, who was touring the Wellfleet site. This Forty Meter contact had been scheduled in advance to allow two former Marconi Wireless sites to make contact with Princess Marconi. Princess Marconi is in the United States touring sites which were owned and operated by her father, Guglielmo Marconi, and his wireless company.





Using the call sign WA2GM of the Marconi Chapter 128, of the Quarter Century Wireless Association the Ocean – Monmouth Amateur Radio Club made the contact. OMARC President Jeff Harshman, N2LXM was the control operator, with Steve Rosen KB2PGA, Quarter Century Wireless Association representative in attendance also in attendance were OMARC Members Bob KA8SAF and Alan KB2RR as witnesses.

Matt Thomas, W1MST, is the managing editor of AmateurRadio.com. Contact him at [email protected].

A reminder that the historic alternator TX on 17.2kHz VLF will be sending a message this Sunday twice. They usually QSL via the amateur QSL bureaus. See http://alexander.n.se/in-english/saq-transmission/ for more details of this and other transmissions.

Some years ago I copied the transmission, QSLed and am the proud owner of one of their QSL cards. It is not hard to copy in Europe unless you have local noise problems. A small tuned loop is all the antenna needed. There are even a software receiver available free on the net capable of receiving the transmissions with a suitable antenna connected to the PC. The SM6LKM software receiver is excellent and covers 0-22kHz. It makes a very useful VLF receiver. I describe it on my YouTube Channel G3XBM.  See https://www.youtube.com/watch?v=TDxRhQYg7lQ.

Roger Lapthorn, G3XBM, is a regular contributor to AmateurRadio.com and writes from Cambridge, England.