DX RX

The Doctor of DX prescribes the
answers to your problems, low and
high, near and far.

A how to of what for, by Mike(aka Billy)Graham, K7CTW

Random Thoughts
Bob Mitchell, W1NH

On April 10th I had the pleasure of visiting with some of the folks from the North Country Amateur Radio Club, who were holding a flea market and VE Session in Twin Mountain at the Town Hall. One of the folks I met and had a great “ragchew” with was Bob Mitchell, W1NH. As my biddy buddy Ed, K2TE, will testify, anyone who has ever spent any time at all on 80 CW (and occasionally 40 CW) will have encountered Bob and his ‘big sig’ from Raymond. Bob IS ‘Mr. 80 Meters’. He has (I hope I remembered this correctly) 334 countries confirmed on 80 CW, obviously some of which are now deleted countries. And on the current list he only needs six! Sheesh!!! Ed and I thought we were doing well. He’s been on 80 since The Last Supper, I think, and his wealth of knowledge of that band and its vagaries over a sunspot cycle of 11 years is immense.

There has been more occasions than I care to remember that Ed and I have talked about his ability to hear stuff on 80 CW that no one, and I mean no one, else is hearing. He told me that the secret was very simple - nothing more than a couple of strategically placed Beverage receiving antennas for that band. While we were chatting I asked Bob what he thought of Beverage antennas made from slinkies, as I had been giving that some thought due to the size of my lot. He was not overly enthusiastic about using a ‘loaded’ antenna of any type. He stated that nothing out-performed a well-designed and laid out full-size Beverage for reception on 80 Meters. So unless I can find some invisible paint and sneak a wire out through the woods behind my place, I will never attain the type of 80 Meter performance he and other low-band DXers achieve.

Bob also confirmed what I had been told about his transmitting antenna array. He has four switchable phased verticals aimed NE- SW for DX optimization and for Grayline work. Each vertical also has a number of 80-foot ground radials. When I asked him what he thought about using 4 verticals in a switchable rectangular array for multi- directional capability, he said he felt that, for starters, the impedances were so complex as to be almost impossible to match. And when you stop to think about it, it doesn’t matter a hoot how good your transmitting antennas are if your receiving antennas are not going to pull in the weak ones.

All in all, it was a thoroughly enjoyable visit with Bob, and I’m looking forward to another visit with him at Rochester in May. I have sorta hinted around that Ed and I would enjoy paying him a visit (sorry I didn’t ask your permission first Ed) to view firsthand his big array. I hope to come away with some useful knowledge from that visit.

Y2K & Power Flops?

I also ran into Tom Mangels, WA1JVV, NH Section Traffic Manager, at the NCARC Flea Market. He was one of the VEs there and I was very impressed with the number of people who were either taking their first series of exams or were upgrading. I took a rapid headcount and 16 people were still in the session, with 4 or 5 having already completed. One lady was running around the building with a smile so big it was infectious. She had just passed her 5 WPM and Tech-Plus exams. Another person I chatted with told me that he was taking the exam because he was worried about the effects of Y2K and how it might impact power distribution. Whether or not that is a valid argument is open to debate, but a friend of mine who came to the last NARC meeting and wants to get his ticket stated the same thing. Hmmmm? And, as most of you now know, the City of Nashua will most likely be activating the EOC at the downtown alarm center right next to the library on New Year’s Eve. Maybe there is something to all of this stuff. I’ve tended to “pooh-pooh” much of it insofar as local government is concerned, figuring that surely our local and state officials and service providers would certainly be prepared. But if we rely on power coming to us from “outside” sources (and we do), perhaps we shouldn’t take it so lightly. I dunno, but food for thought. It probably won’t hurt to have some extra petrol on hand in the truck’s tanks to siphon off in the event that something DOES happen.

17M Double Extended Zepp

On the way home yesterday, I was listening in on one of the repeaters up north and a couple of fellows were discussing how hot it has been lately on the bands. This one particular fellow stated that he has been doing a tremendous amount of work on 17 Meters using his crossed 40 Meter dipoles. He mentioned that his dipoles are fed with ladder line and he has a switchbox at the apex to switch them. His calculations show that a full-sized 40 Meter dipole is just about the right length to act as a double extended Zepp on 17 Meters. He said that he has not used a linear amp once, and has consistently been working all that shows up while he’s on the air. (WOW! I just heard a spot on the DX Cluster for a VR2 - Hong Kong on 17 at 1305Z - it is hot!!). Given that a linear amp adds less than 2 S-units of gain, he figures he’s saving money, as he doesn’t have to give it to PSNH. The solar flux index has been up around the 130-140 range the past week or so, and is still climbing. It’s going to be a great DX season for all of us who want to chase it, with or without mega- antenna farms and amplifiers.

Antenna Comparisons

Earlier this morning I had a most enjoyable and rather lengthy QSO on 40 CW with a Brit fellow operating ‘stroke EA5’. He has two towers - a 40-footer and a 70-footer. On the 70’ tower he is using a Cushcraft 2- element 40 Meter monobander 40-2CD, and on the 40-footer he has a Cushcraft S-3 tri- bander. He mentioned several other antennas. But most of his aluminum comes from Cushcraft. I mentioned that my QTH was less than ten miles ‘as the crow flies’ from Cushcraft and also that I was putting up my X9 this summer. He went on to relate how he also had an X9, but that it was now lying under his deck. He had taken it down after some ‘extensive’ comparisons. He related as how the X9 on the 70-footer never once performed any better than the S3 on the shorty. He stated that all received signal reports were ‘about the same’. The point here is simple; off-handed comparisons are quite frequently very inaccurate and open to numerous questions. Several come to my mind immediately:
  1. How far away were the stations he was doing the comparisons with?
  2. What was the time of day or night?
  3. Long path or short path?
  4. How accurate were the S-meters used to measure the signals? Two or three, or even four dB of difference in signal at the antenna will not show on anyone’s S-meter. They just are not that accurate. Many more questions could be asked, but it is a moot point. The time to really ‘wring out’ a big yagi is not necessarily when band conditions are excellent. Wait till conditions worsen. Consistent performance (whatever our expectations are) over a period of years, not days/weeks/months, is the key to determining if an antenna is for you. Don’t get ‘sucked in’ by unscientific off-hand comparisons. If you’ve researched and, more importantly, used a given antenna under differing conditions and if it meets your needs, go with it - and stick with it. In the long run, you’ll be glad you did.
    73 es Good DX, de     K7CTW

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