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I was fortunate to attend the SOTA Rocky Mountain Rendezvous that occurred from July 31 - Aug. 3 in Buena Vista, CO. This year's Rendezvous was a no-host affair with informal gathering of SOTA Activators. Participants consisted of  locals, visitors in rented cabins, campers, etc.... It was a great time. The group that I was a part of rented a house about 12 miles outside of Buena Vista and little did we know there were two SOTA peaks within a 5 minute drive to the base of the mountains. Staying in the rented vacation home were Fred KT5X (aka WS0TA), Guy N7UN (ask NS0TA), John K1JD, Doc K7SO, Alan NM5S, Curtis KC5CW, my grandsons Reid KF5GYE and Boogie KF5GYD (both General Class), my XYL Cris KC5HZQ and myself.. Camping, about 5 minutes away at the base of Kaufman Ridge, was Steve, WG0AT along with Acorn and Barley.

We had a Dutch cookout on Friday night which attracted all the finest people including, Bryan N0BCB w/XYL and friends,Walt W0CP w/XYL,  Dave NN5K w/XYL. Seems like some others, but these are who I can remember. We had a great time grilling burgers, steaks, brats, etc... and swapping SOTA stories.

The RMR coincided with the 14er event put together by Bob K0NR, who stopped by the SOTA house on Saturday night along with his XYL Joyce, K0JJW. The event is an annual event (ham14er.org) which encourages hams to actuvate one of the 14,000 ft. summits in Colorado. As a SOTA chaser and activator, it is a cool event with lots of activity on both HF and VHF.

While in Colorado I was able to active 3 Summits, Kaufman Ridge (10,700 ft. ASL) W0C/SP-081, Horseshoe Mountain (13,900 ft. ASL) W0C/SR-064 and Mt. Sherman (14,034 ft. ASL) W0C/SR-061.

My grandsons and I were fortunate to be able to climb Kaufman Ridge with Steve, WG0AT and he two SOTA Goats, Barley and Acorn. We had a great hike and my grandsons loved interfacing with the goats. Steve did a video of our climb and it can be found at the link below.

https://www.youtube.com/watch?v=EcWGh7Wl3Gw


                                                               KF5GYE (Reid), Barley and Acorn on Kaufman Ridge



                                                          K1JD and AD5A on Mt.Sherman, 14,034 ft.


                                                             KF5GYD (Boogie) on Horseshoe Mt. (13,900 ft. ASL)


                                                      Panorama from Horseshoe Mt. (13,900)

It was a great trip and something all SOTA activators should consider doing.
Mike Crownover, AD5A, is a regular contributor to AmateurRadio.com and writes from Texas, USA. Contact him at [email protected].

For the first time ever I have been spotted on all the five bands that my Ultimate3 QRSS/WSPR kit (G0UPL design) is transmitting on. This is after 2-3 days of transmitting.

Right now I am using the beacon for discovering if the bands should open up on 24 and 28 MHz. The other three bands, and especially the 14 MHz band, serve as references to tell me that the transmitter is working. My antenna is not so optimal so I would be surprised if I am spotted far outside Europe. It is an end-fed 5 m long half wave vertical dipole which isn’t too bad for 28 and 25 MHz, and probably not very good at all on 21, 18, and 14 MHz.

Sverre Holm, LA3ZA, is a regular contributor to AmateurRadio.com and writes from Norway. Contact him at [email protected].

We will be shooting AmateurLogic 69 Saturday August 9th at 7:00 PM CDT, 0000 UTC.

Tommy’s got something special to show you this time!

You can watch the live stream at live.amateurlogic.tv.

And join us in the chat room at amateurlogic.tv/chat.

George Thomas, W5JDX, is co-host of AmateurLogic.TV, an original amateur radio video program hosted by George Thomas (W5JDX), Tommy Martin (N5ZNO), Peter Berrett (VK3PB), and Emile Diodene (KE5QKR). Contact him at [email protected].

As mentioned in Part I, my construction of the MØBMU-designed Scopematch has proven to be the most valuable piece of test gear in my LF station. If you plan to become active on our new 630m band, it is well worth taking a few hours to build as it will make antenna tuning much, much easier than trying to get your antenna tweaked using other methods.

After building and installing the new Scopematch, a quick check of what I thought had been a properly-tuned system, surprisingly revealed that my 2200m antenna was neither matched correctly nor tuned to resonance! In spite of my poor-tuning (using the system shown in my last post), I had still received a number of encouraging reception reports from VE6, Washington and Oregon, giving me false and undeserved confidence in my earlier tuning attempts. The Scopematch soon changed all that.

The complete building instructions and operating description for the Scopematch may be found in "Tuning Aids for the 136kHz and 500kHz Bands" by Jim Moritz, MØBMU.

Source: Tuning Aids for the 136kHz and 500kHz Bands by Jim Moritz, MØMBU

As can be seen, a small RF sample taken by the Scopematch is coupled to the inputs of a dual-trace oscilloscope...one channel displaying the antenna current waveform and the other displaying the voltage waveform. When the antenna system has been tuned to resonance and matched to 50 ohms, both sine waves will be equal, in both phase and magnitude as shown below.
Such a condition is ideal and virtually guarantees that your transmitter is looking into a non-reactive 50 ohm load. Many transmitter designs utilized on LF employ inexpensive switching MOSFETs operating in either class-D or class-E modes that cannot tolerate any reactance in their output load. The end result of such a condition quickly produces a growing pile of dead MOSFETs!

Source: Tuning Aids for the 136kHz and 500kHz Bands by Jim Moritz, MØMBU

If the system is not tuned to resonance, the phase of the waveforms will not be the same and one waveform will lead the other. Whichever waveform is doing the leading indicates whether the antenna is tuned above or below the desired frequency so that proper corrective measures can be taken to achieve resonance.

Source: Tuning Aids for the 136kHz and 500kHz Bands by Jim Moritz, MØMBU

The condition shown above illustrates the smaller waveform (V) lagging the larger current waveform (I) which indicates the antenna is capacitive or too high in frequency.With 'I' being greater than 'V', the resistive component of the load measures about 20 ohms.

The condition shown below indicates resonance but with 'V' being greater than 'I', the resistive component of the load measures about 80 ohms.

Source: Tuning Aids for the 136kHz and 500kHz Bands by Jim Moritz, MØMBU

The impedance match will be indicated by the amplitude of the two waveforms. Depending on which waveform is higher or lower indicates if the resistive impedance component is higher or lower than 50 ohms. Actual impedance values can be calculated from Ohm's Law using the sampled
waveform values.
It is fascinating to watch the scope patterns during windy conditions when the antenna's large tophat section is being blown around, causing slight changes in impedance and resonance. The two waveforms will expand and contract as well as shift phase slightly...almost as if the system is alive and breathing!

My 2200m antenna - resonant and matched & a thing of beauty!

Jim's article goes into much more depth as well as showing alternative methods of construction and is very much worth studying. Over the last few years I have suggested the Scopematch to several LFers who, like me, now wonder how they ever lived without it!


Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

to remind anyone, but I will, anyway. THIS coming Sunday is the NJQRP Skeeter Hunt! And there is still time to sign up for a Skeeter number – all the way until 0400 UTC on Sunday morning.

We have 140 Skeeter’s so far, warming up their wings and ready to take flight. Please consider joining in on the fun.

All the rules can be found at www.QSL.net/w2lj or, you can just click on the Skeeter Hunt page tab above.

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].

Tonight is the last night my shack is being used as a bedroom. Hopefully I shall be able to operate beyond 1745z tomorrow if I want to. I am also unable to come on for the UKAC session on 2m this evening for the same reason: my shack is  a bedroom for the third night.

10m WSPR unique spots until QRT at teatime

These last few days have been exceedingly fatiguing (stroke).  Not sure if this just a bad week or whether it is extra tiring having the little ones around: although I enjoy having them it is at least twice as tiring for me: I worry about them but am too feeble to sort out things. This makes me feel SO tired.  We’ll see if I feel less tired when they go home.

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

As I posted at the end of June I was almost on the point of giving up on HF due to the high levels of QRN/M suffered at home.

In desperation I had been looking at some of the noise cancellers available from MFJ and others. I had heard conflicting options on their effectiveness but was willing to try one if I could obtain one cheaply. The MFJ units are in my opinion expensive to purchase new so I bid on several that came up second hand on eBay but they invariably also went for silly money. I was even contemplating building an home-brew one from the numerous designs available.

Then I discovered the WiMo QRM Eliminator, made by the German company WiMo Antennas and Electronics. Several online reviews and numerous YouTube videos seemed to indicate its effectiveness and taking up the then summer discount offer I ordered one for the princely sum of €147 including postage, around £116.

Due to heavy demand and low stock levels following the International Ham Radio Exhibition at Friedrichshafen I was told the unit wouldn't be available till the middle of August, so I was pleasantly surprised when the unit turned up last Friday morning.

New toy in time for the weekend ;-) Thank you @wimo_de pic.twitter.com/4Xfuv5ccHB
— Andrew Garratt (@nerdsville) August 1, 2014

I have connected it up and briefly tried it out and am impressed, as this video illustrates.


Even using one for a short time I would agree that they are something of a black art to set up and use and can understand why people might consider them useless, but this may be due to lack of understanding of how they work.

I have created a diagram showing a typical scenario.

The operators main antenna is designed to pick up distant signals, not necessarily DX but signals not emanating from the immediate vicinity, however they will also pick up locally produced QRM as shown, perhaps generated by a neighbours TV or PLT device. 

The QRM eliminator has a second antenna which isn't as efficient as the main antenna and ideally just receives the local QRM at a similar level to the main antenna. The device then takes this second signal and inverts the phase so when it is mixed with the main antenna signal the QRM is cancelled out.

The principal is quite simple, if you take two in phase signals and combine them you will end up with a signal with a larger amplitude. However if the signal is 180 degrees out of phase, the positive and negatives of the waveform cancel each other, producing a null signal. 

The tricky part is making sure the noise antenna just picks up the noise, if it picks up the main signal then that will also be cancelled out. The WiMo unit has three controls a gain and two phase controls it is a case of altering all three to maximise the cancelling effect without losing the main signal.

At present I just have several meters of wire running as the noise antenna along the side of the shack and this seems to fairly effective.

The unit is powered from 12V and can be left in line, but requires the PTT/TX-GND signal from the CAT/Linear socket from the transceiver to activate a bypass when transmitting and I don't have the appropriate 8-pin plug at present. If the unit is powered off the bypass is automatically engaged.

All in all, first impressions are good and looks like a worthwhile purchase.
Andrew Garratt, MØNRD, is a regular contributor to AmateurRadio.com and writes from East Midlands, England. Contact him at [email protected].