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Author Topic: G5RV  (Read 3087 times)
G3RZP
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« Reply #15 on: April 23, 2011, 02:38:12 AM »

Apparently the cavity magnetron was discovered in Japan in about 1938 or 9, but they had no use for it.......On its own, it's only good for heating things. You need a T/R cell, a reflex klystron and a silicon microwave diode, and of those, only the klystron existed at the time.

The Marconi TF144 signal generator of 1938 used a flexible concentric output cable, although I don't know what the insulation was. By 1943, some of the polyethylene insulated coax cables that the RAF used had become obsolete and been replaced by new ones, although the RAF Shortwave Communication Handbook of 1943 said that polyethylene was in short supply.

The second edition of the Amateur Radio Handbook, RSGB, 1939, lists a number of flexible coaxial cables, although some of them would be very lossy with PVC insulation. There were some with polyethylene thimbles, though.

So there were flexible coax cables around, at least over here. there could well have been some in Germany, too.

I believe the 'Collins coupler' was originally an antenna tuner rather than a tx output tank.
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N3OX
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« Reply #16 on: April 23, 2011, 07:07:58 AM »

Much of the problem people with the G5RV and its variants has nothing to do with the technical merits of the antenna.  It has nothing to do with what bands the G5RV is good on and which it's not so good on.  It's pure prejudice.

W8JI did a test where he installed a G5RV and a halfwave 80m dipole at the same height, and found that a G5RV was almost always exactly equal, except when he actually called the antennas by name.  Then, the antenna he called a G5RV was significantly "weaker" to the guy on the other end.

http://www.w8ji.com/g5rv_facts.htm

But sometimes he flipped the names.  It didn't matter if he was calling the dipole the "G5RV" or telling the truth about which antenna is which.

There are some instances in which you can make your signal stronger by lying about the type of antenna you're using.  Isn't that cute?
« Last Edit: April 23, 2011, 07:09:45 AM by N3OX » Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
W5LZ
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Posts: 477




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« Reply #17 on: April 23, 2011, 07:13:13 AM »

About that G5RV.
Mr. Varney made that antenna as a 20 meter antenna, that's all.  It just happened to work on harmonically related bands (with a tuner).  There was enough 'controversy' at the time that Mr. Varney explained the 'what/why' of the thing several times.  You should be able to find quotes about that on the internet, it's not a 'secret' by any means.
Why do you see so much 'amazing' claims for that antenna?  Think about it, it works on those harmonics, and is a "money maker" for builders.  Does it really work -well- on bands other than 20 meters?  Not what I'd call 'well', but it works, and if it 'fits' your situation, good.  Just don't expect 'miracles'.
And then you've got all the 'copies'/variations of that G5RV antenna that sometimes have no obvious 'kinship' at all.  They must 'work' for someone...
Paul

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N2EY
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« Reply #18 on: April 23, 2011, 10:35:48 AM »

Mr. Varney made that antenna as a 20 meter antenna, that's all.

Sorry, that's just not true. The original articles show that G5RV made it for multiband use from the beginning.

 It just happened to work on harmonically related bands (with a tuner).

Not true either. The original design works on several bands without a tuner, if you use a typical hollow-state transmitter of the same vintage as the G5RV design.

73 de Jim, N2EY
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G3RZP
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« Reply #19 on: April 24, 2011, 03:02:51 AM »

BTW, when Louis published, 40m was 7.0 to 7.15 in Region 1. We lost the top 50 kHz at the  radio conference in Geneva in 1959.

Thanks to the IARU, we got the 100kHz back at WARC03, effective 50 years after we lost those 50 kHz.
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N2EY
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« Reply #20 on: April 24, 2011, 04:39:03 AM »

BTW, when Louis published, 40m was 7.0 to 7.15 in Region 1. We lost the top 50 kHz at the  radio conference in Geneva in 1959.

Thanks to the IARU, we got the 100kHz back at WARC03, effective 50 years after we lost those 50 kHz.

Thanks! I did not know that!

73 de Jim, N2EY
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G3RZP
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« Reply #21 on: April 24, 2011, 11:22:10 AM »

Jim,

having lost the top 50kHz, for years we had broadcaster si the 100kHz we did have1 One of the worst was Radio Pakistan on 7010.

Now we have Radio Tehran on 7200. What is needed is an international contest centred on 7199.5 running 24 hours a day.......

There's a lot of countries that have footnoted the Radio Regulations and run commercial stuff in 7 to 7.2. The good thing is that if they get the hell jammed out of them, they can't complain.

Still, we've drifted from G5RV. I guess, though, that I'm the only guy here who has had G5RV and XYL stay overnight with him on a number of occasions.....he liked kippers for breakfast.
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W0BTU
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« Reply #22 on: April 24, 2011, 12:02:41 PM »

What is needed is an international contest centred on 7199.5 running 24 hours a day.......

That's funny! :-)

But I wouldn't try it. I heard of a guy here in the USA who zero-beated Radio Moscow, and got a citation from the FCC.

Quote
... had G5RV and XYL stay overnight with him on a number of occasions.....he liked kippers for breakfast.

Hey, that's interesting. I think that it would be interesting to us all if you could share any experiences with Mr. Varney with us. :-)
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G3RZP
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« Reply #23 on: April 24, 2011, 12:59:36 PM »

The answer to the FCC is that according to the international Radio Regulations stations not authorised to use the frequency cannot suffer interference from stations authorised so to do. So no matter what you do, you are not causing harnful interference, although they may be doing so under Article 4.4.

Over here, it's very much a case of if you are a primary user, any other service  has to put up with interference. If you are secondary service, you must defer to a primary service, but not another secondary service. That means that in 80m, for example, where amateur and maritime mobile have equal status, they can't complain of interference from amateurs. If it came to court, I doubt the FCC would win in cases where amateur is primary and there are no other authorised primary services.....The US has signed the treaty and it is international law. This was why back in 1983 when the Australian Navy complained about being QRMed on 18 Mhz, they had to suffer - but nobody in the Australian Administration  had told them that the band had been reassigned!

So jamming a Russian naval teleprinter on 14127 by calling CQ all over them is quite legal...
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W0BTU
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« Reply #24 on: April 24, 2011, 01:27:28 PM »

I see what you're saying. When that station tried to jam Radio Moscow, it was back in the days of the USSR, and Radio Moscow was an authorized user.
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G3RZP
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« Reply #25 on: April 25, 2011, 01:44:27 AM »

Mike,
Even that would have depended on where Radio Moscow's target area for the broadcast was. A peculiarity (which we still have today in slightly different form) is that a BC station in the band 7.2 to 7.3 must not be targetting Region 2 i.e. the Americas. In the earlier days, it was BC between 7.1 and 7.3 that were supposed to avoid targetting R2. Radio Regs 5.142. In R2, 7.0 - 7.3 is amateur as primary.

I just wonder how much longer SW BC will go on for. The BBC was supposed at one time to have the most listeners and that was something like 1 for 100 watts transmitted.
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W3LK
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« Reply #26 on: April 25, 2011, 04:33:40 PM »

I'm 68 and started listening to the Beeb as a 13-year old. I have been a steady listener over the years. Now, there's nothing of the Old Lady left worth listening to. Sad

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A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
G3RZP
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« Reply #27 on: April 26, 2011, 01:35:23 AM »

Even the domestic weather forecasts aren't as detailed as they were back in the 1950s when I was a kid.
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AC4RD
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« Reply #28 on: April 26, 2011, 03:52:48 PM »

I'm 68 and started listening to the Beeb as a 13-year old. I have been a steady listener over the years. Now, there's nothing of the Old Lady left worth listening to. Sad

Ying tong iddle i po!


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N0ZNA
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Posts: 115




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« Reply #29 on: April 30, 2011, 08:16:58 AM »

I am lucky,have 3 acares and not a limitation on what i put up.I have a dipole that has a homemade balum,and 124 ft #8 wire on each end.Johnson vicking matchbox and it tunes from 6- to 80 mtrs.I run a old ts520s and dont have 160.I think a dipole would be a better antenna for you if you have the space.73s de JW
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