Trials and Errors #62: Celebrating Innovations and Innovators!

In number 62, W7DGJ describes five of his favorite "mantras" used by creative people in their pursuit of innovation. Along with the mantras, Jensen highlights five innovators or radio operators who have provided significant value to the rest of us via their work. Comment on the article here, or add your viewpoint (positive or negative)! Here's the article link. Dave, W7DGJ

 

There's quite a bit more to be said (some not very flattering) about Gernsbeck and I only know part of the story.

 

If I were tasked to pick their order of importance, I would rank them in this way:

1. Innovation Mantra #4: Be Curious
2. Innovation Mantra #1: The "How" is in the "What"
3. Innovation Mantra #5: Embrace Uncertainty, Paradox, and Ambiguity
4. Innovation Mantra #2: Relinquish the Need to Defend
5. Innovation Mantra #3: You Can't Create from a Low-Grade State

 

Thanks Duane. That's a fair statement. I wrote it in no particular order, as all five are critical, but the "Be curious" element is especially important. Dave, W7DGJ

 

Hi Jeff - Just like David Sarnoff, he's one of those innovators who drove forward, sometimes over other people. Everyone has their positive and negative qualities, right? But he DID bring a relatively cheap radio to the masses, he DID bring thousands of "radio boys" into the world of Amateur Radio, and he DID organize and promote A.R. at a time when the US Navy could have just taken the whole ball of wax and we'd have nothing. So, he was a high impact guy, with little credit given to him by our official organization, due to egos at the time (Gernsback and Maxim). Dave, W7DGJ

 

There are many myths about G5RV and the antennas he developed. Unfortunately, the article perpetuates some of them.

Here's the straight dope:

The "G5RV" is a combination of dipole length and matching section length and impedance which gives a "reasonably low SWR" on "all HF bands". BUT....people forget the rest of the story:

1) When the G5RV was developed, "reasonably low SWR" meant "less than 4 or 5 to 1". With the transmitters then in use, using a relatively short feedline, that was good enough. The usual concern was whether the transmitter would load up, not the feedline SWR. Many hams didn't even have SWR bridges, or had very crude ones, and simply assumed that if the transmitter loaded up, and they made QSOs, and nothing started smoking or arcing, they had "low SWR".

2) "all HF bands" back then meant 80/40/20/10. Plus, outside Region 2, "80" was 3.5 to 3.8 MHz and "40" was 7.0 to 7.1 MHz. 160 is MF, and was meant to be handled by tying the feeders together and working against ground as a top-loaded vertical. 60, 30, 17 and 12 meters would not be amateur bands for a few decades yet. 15 meters only became an amateur band in the early 1950s.

3) The G5RV was developed long before antenna modeling and optimization, so there's a lot of assumptions and hand-waving that are quite questionable by today's standards. Model and optimize a G5RV and you wind up with a ZS6BKW.

4) The G5RV, ZS6BKW and similar are just center-fed dipoles with feedline arrangements that facilitate multiband operation. They're not magic nor are they junk - if properly built and installed. Often they are not.

5) "Window line", aka "Twin-Lead with holes" is not lossless, or even all that low-loss, particularly when operated at high SWR. G5RV recommended real open wire line, which is NOT the same thing as "window line".

6) Almost anything conductive can be "forced" to radiate SOME RF, given a "tuner" with a wide-enough matching range. What suffers is efficiency.

An antenna system which is only, say, 10% efficient - that is, one which wastes 90% of the RF from the transmitter as heat - will still radiate 10%. 1000 watts going to an antenna system that is 10% efficient will radiate as much RF as 100 watts to an antenna system that is 100% efficient.

7) Anyone and everyone interested in the G5RV and similar should take the time to read and understand the original articles. But so few actually do. The original 1958, 1966 and 1984 articles are attached, plus one on the ZS6BKW. Note that G5RV says in 1958 that the antenna was developed and deployed right after WW2, and used until he went to Venezuela in 1955. Note also that there are two versions presented.

8) HF has incredible "dynamic range". By this I mean that there are times when a few watts into a mediocre antenna will result in amazing worldwide DX - and times when the legal limit into a gigantic array won't be heard across the county line. 1958, when the original G5RV article appeared, was at or near the peak of the best sunspot conditions in recorded history (Cycle 19). So amazing results reported have to be taken with the conditions in mind.

9) With most wire multiband HF antennas, the formulas and dimensions are....starting points. Often, adjustment is required because of what appear to be minor differences in location or construction. It would be great if we could just build such antennas per the published dimensions and have them work perfectly right off the bat, but that's not always the case.

G5RV didn't face opposition, nor did it take him 12 years to develop his antennas.

It is somewhat of a mystery as to why it took so long for his antennas to become well known in the USA. Perhaps there was a bit of "NIH" (Not Invented Here) bias?

73 de Jim N2EY

 

Jim, outstanding write up! Thanks for putting it all in one place.

And it was made of what he could get in England after WW2. Not the best or first choice of materials, just what was available.


The design has its dans but I believe the enthusiasm is misplaced. Anything will work, even an incandescent light bulb, as Tom Schiller says.

 

Thanks Jim, an interesting addition to the material.

Please note: this short piece on G5RV was not a technical dissertation on the antenna, nor was it meant to be anything other than a piece to celebrate one element of ham history and, in particular, the creativity of one particular innovator. I don't see anything in my piece that perpetuates "wrong thinking." There is NO TIME IN RECORDED HAM HISTORY when someone built an antenna and didn't have others commenting/complaining/griping or "making suggestions." It's just not possible -- it's in the nature of the amateur. Also, you mentioned that it didn't take him 12 years? And yet, you state that he was using his design in 1946 (as my article correctly stated) and that it was first published in 1958. Jim -- that's 12 years of fussing, changing, improving, redesigning, arguing with other hams, etc. He wasn't happy until he finally had the design the way he wanted it and published that in the RSGB bulletin. I would very much appreciate it if you could remove your barb about my article perpetuating inaccurate information. Thank you, Dave W7DGJ (PS - not disputing your technical comments about his antenna at all. But there's been thousands of them sold, and up to just recently it was still a design sold by MFJ - crates of them.)

 

You're welcome!

Understood. But that particular antenna has much lore connected to it - and much of it is false.

Never is a very long time. Can you point to examples of people complaining and griping about the G5RV prior to 1958?

I disagree. In my experience, it is not unusual for amateurs to do something and only after years pass by do they publicize it - not because they are "fussing, changing, improving, redesigning, arguing with other hams, etc." but because they are busy with other things, don't consider their idea to be that unusual, or can't find a publisher.

From reading G5RV's articles, it's clear to me that he devised the antenna even before UK amateurs were allowed back on the air in 1946, and then proceeded to use it with great success. Then in 1955 he went to Venezuela for a few years. Finally, in 1958, he wrote up an article and RSGB published it. Nowhere do I see any suggestion that he dealt with opposition from others between 1946 and 1958, nor that the antenna went through significant development in that time. Note how short the entire 1958 article is!

I would do that but the editing time has long expired.

73 de Jim, N2EY

 

You're welcome. Please ignore the part about "myths" and such.

Actually, what he used IS the best choice! High quality insulators, real open-wire line, a balanced tuner, etc.

Note too that in the 1958 article he uses 72 ohm Twin Lead (yes, there really was such a thing) or 75 ohm coax - not 50 ohm coax.

It's all about system efficiency - meaning the antenna itself, the feedline, and any matching devices used.

Finally - note G5RV's recommendation to use open-wire line all the way from the antenna to a link-coupled balanced matching unit, with specific lengths of antenna and feedline chosen to present a reasonable impedance at the shack end of the line.

73 de Jim, N2EY