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Author Topic: Amplifier suggestions  (Read 2895 times)
K6BRN
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Posts: 1268




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« Reply #30 on: May 11, 2019, 05:19:51 PM »

Quote
Most of the claimed power specs by end fed antenna manufacturers are dubious to say the least

Yes.  Just as with amplifiers.  Whenever an ICAS rating pops up on a box or antenna, its meaningless noise.  Which is why I posted my own, actual use observations.  About 300 watts AVERAGE POWER on 80M, more on 40M and more on 20M for the EFHW-8010.  Band and height makes a difference - higher is better (both frequency and height above the ground).  Some users have taken the covers off of the matching transformer case and replaced them with screens to increase power handling, with some success.

At the PV ARC meeting I was at today, it was mentioned that about half of the contacts made on the recent Catalina Island IOTA expedition were made with this antenna.  In fact, the glue in the bandpass filters used for simultaneous operations apparently melted, causing some issues.  But the EFHW-8010-2K was not a problem and the antenna just kept on performing.  Other antennas included a hexbeam and 160M wire.

Brian - K6BRN
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K6BRN
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« Reply #31 on: May 11, 2019, 05:24:51 PM »

BTW... I've never had a real problem with "RF in the shack" with a MyAntennas EFHW-8010 or -4010.  But then I DO usually use a common mode choke on ALL of my antennas, about 5-6 feet from the exciter, or up closer to the antenna for the Mosley and vertical.
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W9IQ
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« Reply #32 on: May 11, 2019, 05:52:02 PM »

ICAS of amplifiers has nothing to do with my comment other than it is the same false claim circle of most end fed antenna ratings.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
K6BRN
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Posts: 1268




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« Reply #33 on: May 11, 2019, 06:51:46 PM »

Glenn (W9IQ):

Quote
ICAS of amplifiers has nothing to do with my comment other than it is the same false claim circle of most end fed antenna ratings.

Actually, I was talking about ANTENNA ICAS ratings, too. ICAS seems to be applied like peanut buttler to a lot of things.  For a "marketing" rating for tubes in amateur service invented by...  RCA...?... it sure gets around.  Whether or not it has any meaning.

Otherwise.... There are a LOT of end-fed antenna makers out there, so its just a little hard to figure out just what you are referring to.

I presume that you've used one (an end-fed antenna) and been disappointed...?  Plenty of possibilities, there.  I do not like the HAC ARC stations stub-tuned end-fed.  Forgot the maker.  But not the greatest.

Brian - K6BRN
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W9IQ
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Posts: 3239




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« Reply #34 on: May 11, 2019, 06:58:27 PM »

Brian,

I have examined the failed transformers from your favorite brand, snorkels and all. ICAS is not in my vocabulary.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
K6BRN
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Posts: 1268




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« Reply #35 on: May 11, 2019, 10:45:46 PM »

Glenn (W9IQ):

Quote
I have examined the failed transformers from your favorite brand, snorkels and all. ICAS is not in my vocabulary.

OK. Great.  You don't like ICAS ratings, either.

But.... What does the rest of your very terse statement mean? 

If you have something to share, good or bad, please share it.   I do have good luck with the EFHW antennas and that's why I like them.  So do my clubs.   But in the end, they are just gear, like any other.  So if you have any observations, let's hear them.  You generally have a pretty logical thought process, and I respect that, so I'd like to hear what you've found and your conclusions, which I presume are from "hands-on" examinations.

Regardless...

I've also managed to drive a much lower capacity EFHW-8010 deep into the high SWR zone (likely the interior of the cores reached their Curie temperature) and once this happens, it's much easier to do.  I've opened up the transformer in question, but there is no obvious damage.  I've NOT cross-sectioned the cores.

Never done that with a -2K model, though.  Because I know were to set power limits for those - as I've discussed in MANY posts, as have others.

My units do NOT have "snorkels", BTW, so can't comment on that.

Brian - K6BRN
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VK3BL
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« Reply #36 on: May 12, 2019, 03:21:11 AM »

Most of the claimed power specs by end fed antenna manufacturers are dubious to say the least.

The reason is they don't use a balun. The use an autotransformer - commonly called an unun in antenna parlance. If it were an effective current balun, the antenna performance would suffer greatly. I find it interesting that Danny didn't know the difference.

- Glenn W9IQ

I'll second that.  I'll also add that almost everything made by MFJ has 'dubious' specs when it comes to power output and power handling too.

Heck, even high end brands like Palstar aren't immune.  Their 'AT2K' is rated at 2Kw PEP, yet their flagship 'HF-Auto' only 1800w - and guess which one has significantly bigger components?  Not to mention the minefield that is rating antenna tunes in general...

I wonder where Truman got to?

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J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
W9IQ
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Posts: 3239




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« Reply #37 on: May 12, 2019, 04:31:52 AM »

Brian,

My comment on this thread was that legal limit power and end fed antennas are a bad combination. Initially you seemed to disagree but now you are saying you know the power limits of your 2K transformer. It would seem that you are now agreeing it is less than the legal limit. Am I missing something?

Regarding the failure analysis, I have tried to share some of that with you in other threads but you tend to reject a technical discussion in favor of an "amateur" discussion. So I don't see the point of going down that path with you.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
K6BRN
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Posts: 1268




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« Reply #38 on: May 12, 2019, 06:05:04 AM »

Glen:

Quote
My comment on this thread was that legal limit power and end fed antennas are a bad combination. Initially you seemed to disagree but now you are saying you know the power limits of your 2K transformer. It would seem that you are now agreeing it is less than the legal limit. Am I missing something?

My point is that an operator has to understand the limits of ANY antenna they use, including seemingly large and robust ones like the Mosley TA/CL-53 etc. series and even similar trap verticals - about 600W average power.  Easy to "blow" those antennas up, too, with a "Legal Limit" amplifier capable of 1500 watts of average power.

Quote
Regarding the failure analysis, I have tried to share some of that with you in other threads but you tend to reject a technical discussion in favor of an "amateur" discussion. So I don't see the point of going down that path with you.

I don't think that's really true.  Have we discussed EFHW matching transformer failures before, as related to a design quality problem?  I don't think so.  And if I've forgotten and this is repetitious, my bad.  However, I've always maintained that there are power limits to be observed with EFHW antennas and that buying the highest power version is the best approach.  And I've talked about why - you are virtually echoing those posts.

Regarding professional discussions on an amateur forum...  Professional or amateur, its always best to put information in broader context first and then move to specifics.  It's an old truism that a person who really understands a subject can explain it well to just about any audience.  Richard Feynman and his QED lectures are a case in point.  You usually start from the bottom - and I know - its your style.  My suggestion is that you modify that style to reach the broader audience on the forums. I'm NOT "calling you stupid".

Right now YOU are being deliberately disingenuous and are pretty cranky.  That's OK.  We all have bad days.  You also snapped at Zenki on another recent post over his English, of all things, when he is obviously ESL.  That's not really like you.

If you'd like to take this offline, not as a "battle of opinions" or intellect but as a genuine technical discussion, or otherwise, I'm all ears.  As long as its constructive.  My email should be good on QRZ and you can PM me as well to get the ball rolling.  It's really up to you.  I find many of the hams on the forums are allergic to actually having a personal conversation, which is too bad.  The clubs I gravitate to have pretty lively discussions, which i always enjoy.  And about once a month, I DO have offline discussions that continue forum topics.  WAY better than endless threads.

Best Regards,

Brian - K6BRN




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K0UA
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Posts: 4361




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« Reply #39 on: May 12, 2019, 09:22:01 AM »

I think we can all agree that the new fella just starting out needs a legal limit amp with or without tuner like he need a big gaping hole in his head.

OF COURSE he needs to maximize his antenna systems and first find out his noise level at his QTH and do what he can to mitigate that before he even thinks about getting and amp and all the trouble and headache that an amp brings with it if the antenna systems and not optimized for such high power.  As Jarrod pointed out and many others gently persuaded to get his antenna system in order before even thinking about an amp. Of course the power requirement of a legal limit amp and the hiring of the electrician to install the 240 volt power needed is another concern.

I have been licensed for almost 50 years now, and have 210 countries confirmed since I started being interested in confirming DX countries in late 2017 and I have done it with modest antennas and 100 watts. I have never owned an amp in all of that time.  So to the Original Poster, get your station up and running, gain some experience THEN and ONLY then think about an amp if you decide you need one. "with Mogwai, come much responsibility" to quote and old line from the movie "Gremlins" and the amp is much like the Mogwai, care in its feeding and operation will be your responsibility!  I wish you well.
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73  James K0UA
ARRL Missouri Technical Specialist
N0YXB
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Posts: 1545




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« Reply #40 on: May 12, 2019, 09:33:00 AM »


So to the Original Poster, get your station up and running, gain some experience THEN and ONLY then think about an amp if you decide you need one. "with Mogwai, come much responsibility" to quote and old line from the movie "Gremlins" and the amp is much like the Mogwai, care in its feeding and operation will be your responsibility!  I wish you well.

Good advice.

And this thread has nudged me to try an end fed antenna. Looks like an awesome solution to a temporary issue at my QTH.
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G3RZP
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« Reply #41 on: May 12, 2019, 09:45:16 AM »

Over the last 56 years that I have had a licence, I've used a large number of end fed antennas. Strangely, the most successful was a W3EDP! Also strange is that, in general, where the 'ground' has been good - wet clay - they haven't worked as well as over sandy soil. But I have always used a home brew tuner right at the end of the feeder, with component values adjusted for a working Q of between 10 and 20.
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K6UJ
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Posts: 1358




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« Reply #42 on: May 12, 2019, 10:04:39 AM »

Brian,

My comment on this thread was that legal limit power and end fed antennas are a bad combination. Initially you seemed to disagree but now you are saying you know the power limits of your 2K transformer. It would seem that you are now agreeing it is less than the legal limit. Am I missing something?

Regarding the failure analysis, I have tried to share some of that with you in other threads but you tend to reject a technical discussion in favor of an "amateur" discussion. So I don't see the point of going down that path with you.

- Glenn W9IQ


Glenn,

I agree with your earlier post and this comment.  You are spot on.  I see Brian has created a smoke screen rebuttal to try and cover his tracks  Grin

73,
Bob
K6UJ
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NN2X
Member

Posts: 335




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« Reply #43 on: May 12, 2019, 10:20:45 AM »

SB 220 Amplifier, best bang for the buck...or SB 200

However, using an ENDFED, you might find yourself that the Transmit signal might exceed the limitation of the RX gain for an ENDFED.

In practice though, 500 Watts will be balanced with an ENDFED. This is just from my experience.

With a Yagi (10 - 20) Up at 65ft, I find the receive gain is sufficient to support 1500 watts Transmit. Again, this is just my experience

cheers
C U on the bands

NN2X, Tom
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VK3BL
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Posts: 1789


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« Reply #44 on: May 12, 2019, 09:40:43 PM »

I think we can all agree that the new fella just starting out needs a legal limit amp with or without tuner like he need a big gaping hole in his head.

I have been licensed for almost 50 years now, and have 210 countries confirmed since I started being interested in confirming DX countries in late 2017 and I have done it with modest antennas and 100 watts. I have never owned an amp in all of that time.  So to the Original Poster, get your station up and running, gain some experience THEN and ONLY then think about an amp if you decide you need one. "with Mogwai, come much responsibility" to quote and old line from the movie "Gremlins" and the amp is much like the Mogwai, care in its feeding and operation will be your responsibility!  I wish you well.

Exactly the point I too was trying to make to the OP, Truman.  Instead it turned into yet another flame war that everyone who has ever run true QRO knows - a real antenna system and not $100 usd worth of 'all band magic'.

Soon we will have to call this site 'eFed.net', as that is all we discuss.  I mean, who cares?

Those of us that have designed antenna systems with lobes pointing where we want to work and to handle the power we can use KNOW the difference it makes.  I for one don't feel insecure enough to endlessly point out that a random wire is like a lottery ticket, and thats before you connect the linear.

I've got a dipole at VK3BL and the 80M noise floor is 30dB over S0.  On the other hand, at VK3AGA the exact same antenna down just a few feet is lucky to read S7 on a monster signal.

The moral of the story is EXPERIMENT.  FIND OUT what works for YOUR QTH.

End of story.  Please, can we stop making this 'eFed.net'.  Glen et. al., let people learn for themselves and lets keep this section to Linears please.
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J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
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