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Old 12-03-2013, 11:56   #61
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

Bob,
1) To be brief and direct, your antenna choices should be based on where, when, and on what band/freq you wish to communicate.....
Then factor in how much you can spend($$$), and how much effort/work/construction/etc. you can manage, as well as how much room you have for the antennas, etc....

I think you see where I going....there are MANY possibilities, and it is very difficult for ME to make the choice for YOU, as I have no idea what the answers are to the above questions....

For long-range comms, verticals (on land) will be the poorer of the two antennas when compared to just about any horiz antenna mounted 1/2-wave (or more) high....even a dipole is usually a better choice....
UNTIL you get to the lower end of the HF spectrum, such as 80m, where a decent vertical/radial system can be better than most horiz antennas, since you are unlikely to have the horiz antenna at least 130' high....




2) As to a specific comparison of / opinions on verticals..
Quote:
Originally Posted by deckofficer View Post
John, will a vertical that I've described above in the open setting that is offered by high roof mounting, along with the SG 230 be about the best I can do short of yagis and towers for 20, 40, and 75? I guess since it is a resonant 1/4 wavelength for 40, it should perform good on that band and the auto-tuner will let it work well enough on 75?
You should understand that the actual performance (gain and radiation angle) of a vertical is not only bound by the counterpoise/ground plane, but also significantly by the ground conductivity (both near field and far field)....
Meaning that a vertical over sea water is a good antenna, and at low radiation angles can be quite a great antenna, even beating a yagi on a tower.....BUT...
But, a vertical over rocky or sandy terrain (both near field within a few wavelengths of the antenna, and far field out dozens to hundreds of miles) is usually a marginal antenna.....better than no antenna at all, but seriously compromised vs. a yagi on a tower...and even poorer when compared to a dipole in many circumstances....

The main "reasons" hams use verticals on shore (vs. on boats over sea water) are:
a) no way for them to get a horiz antenna up higher than 1/2-wavelength, such as 130' high on 75m.....
b) No room / no money for a tower and yagi....and no trees, etc. to run wire antennas up on....



Since this is a sailing forum, I don't wish to spend a lot more time on land-based antennas.....
But on the mid to high HF bands (14mhz and up), there is going to be no comparison....meaning the vertical is NOT going to impress you at all, and it will be beat by even small/simple yagi's at heights of 40' or so....and probably even a simple, cheap homebrewed dipole at 40' would even beat the vertical....

On 40m, you'll probably find a full-size vertical (33') with 4 tuned/resonant radials to work well, and will be better on long distance comms than a dipole up 40' or so....and probably better than the delta loop that you were speaking about earlier....
BUT...
But, this probable performance is based on "vry good" far field (and near field) ground conductivity....so if you do not have that in you region of the world, please consider a horiz antenna, mounted as high as possible (use some of those trees!!!), to be the better choice...



Please understand that almost all of the above is a generalization, as I don't have the answers to those questions above...

So, bottom line:
Throw some wire in the trees!!! Put up a few dipoles and you'll be happy...



And, BTW....
Not sure why you were considering a fiberglass pole???
The Rohn H-50 (50' galv steel telescopic pole) is about $150, and is a very good antenna support....
Or, you may wish to look around at some rural areas where many people have abandoned TV towers at their homes....these are usually very light duty 40' - 50' towers that make excellent supports for wire antennas and/or small yagi's, and are usually FREE for the taking...(you take 'em down, they're yours!!!)



Fair winds...


John
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Old 12-03-2013, 12:57   #62
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

Bob,
Just some brief clarifications here...
Quote:
Originally Posted by deckofficer View Post
One idea would be to mount a 32.5' telescoping fiberglass mast on the crown of the roof in the center with a wire inside it. This placement would allow (8) 36' radials in a 360 degree pattern. These radials would slope downward which might help pulling the radiation pattern closer to the horizon. The best feature of using the crown of the roof is the vertical will see a 360 degree unobstructed view.
When dealing with verticals your lowest angle of radiation is controlled by ground conductivity (both near and far field).....the pseudo-Brewster angle....
Sloping radials on an elevated vertical allow a better match for direct coax feed (50 ohms), but have no real effect on the antenna's radiation angle....




Quote:
Originally Posted by deckofficer View Post
I've also heard the verticals are more prone to man made noise.
Yes....but usually not very noticeable as most use of verticals are on the lower HF bands where natural noise (atmospheric noise) predominates....






In addition to my previous post's details on this....
Quote:
Originally Posted by deckofficer View Post
....will a vertical that I've described above in the open setting that is offered by high roof mounting, along with the SG 230 be about the best I can do short of yagis and towers for 20, 40, and 75? I guess since it is a resonant 1/4 wavelength for 40, it should perform good on that band and the auto-tuner will let it work well enough on 75?
Understand that while "dx antennas" for 75m/80m is my forte, they aren't a "one-size-fits-all" subject....and cannot easily be discussed here in this forum....
So, again, not knowing the answers to the overall questions regarding your antenna applications, it's tough to be specific.....
But, in general I'd say throw up some wire in the trees (dipoles, loops, etc....maybe even a single-band, coax-fed, vert pol full-wave loop for 80m) and see how you like the results....this costs little and you can always use the wire for other antennas, should the results not be to your liking.....


Good luck and fair winds...


John
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Old 12-03-2013, 13:06   #63
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

Bob,

One other note, hopefully providing a bit of grist for the mill.

If my goal were to communicate over long distances....2000 to 10000 miles or so....I would opt FIRST for a single-band vertical dipole located with the lower end near the ground.

These have an extremely low vertical takeoff angle...exactly what you want for DX. They also work very well over land from many locations.

For the first 7 years I lived in this house, I had the following antennas:

1. an all-band commercial folded dipole, 120' long, strung between two trees at about 30' height.

2. two vertical dipoles tuned for the 20m and for the 15m amateur bands.

3. A coaxial antenna switch which allowed me to instantly switch to any one of these three antennas.

My house is located about 300' above sea level, about 1 mile west of National Airport....about 40 miles from the sea, and just over a mile from the Potomac River.

Over 15 years and thousands of transmissions on the various daily nets, and many hundreds of listening and testing hours, I found the following:

1. 90-95% of the time the vertical dipoles beat the horizontal dipole hands down, and by a wide margin;

2. very rarely signals on the horizontal dipole were almost as strong as on the vertical dipoles; I attributed this to relatively rare high-angle propagation conditions.

The 20m vertical dipole works almost as well as it does on my boat. For example, I can easily work into Europe with a 5-10 watt QRP rig, just about at will. When I got a K2 a few years back, I worked 70-some countries in just two weekends...with 10 watts output!

A few years ago I put up an end-fed inverted-L antenna. It's about 80-90' long and about 50' high at it's highest point. This has turned out to be a fantastic antenna. I can work all bands with it (and a Palstar AT1KM tuner) and religiously get "fantastic" signal reports on the 40m band which I work every day.

HOWEVER, on 20m the vertical dipole -- the only vertical dipole I still have -- still beats the inverted-L every time on 20 meters.

Try it. Throw up a cheap temporary one, made of any kind of insulated wire. I use THHN 10-guage stranded, found at Home Depot. That's robust enough to last for years in a land station setup.

Cheers,

Bill
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Old 12-03-2013, 13:23   #64
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

Olaf,
Sorry we really got off topic, didn't we!!!



I'm not completely clear on whether you are doing a new install yourself, or someone else is doing this, or someone else has already done this "new
installation"....but in any case, we can give you some assistance....
First off, place the remote auto-tuner back near your antenna, not at the Nav Station....(but you don't have to go to "extremes", as having it a couple feet away from the backstay is fine!!!)
Quote:
Originally Posted by olaf hart View Post
I am sorting out an SSB setup in a 36' boat. The old installation had a manual tuner at the Nav Station and good thick copper strap to the keel bolts, and an external lead keel.
The new one has an automatic tuner (sg239) in a waterproof case, which I want to put high in the lazarette at the base of the back stay antenna.
How important is it to run new copper strap back to the existing strap? The distance is about 15'. Would wire do the job just as well?
Or should I put the tuner at the nav station like the old manual one?
1) Remember, anything works to some extent....so it's just a matter of how well you wish your system to work...


2) Even large wire will have more inductance than copper strap, and with longer runs (> a few feet) copper strap is what I'd recommend in order to allow you to use a direct sea water connection / using the sea water as your antenna's counterpoise/ground plane.....
Run 3" wide copper strap from the tuner all the way to the closest keel bolt, AND to underwater metal closer than the keel bolts (such as a bronze thru-hull and/or shaft strut, etc.)


3) You CAN use wire, wire WILL conduct the RF energy....
But the wire will also act as part of your antenna's counterpoise/ground plane to a much greater extent than the copper strap would....and thereby reducing the effectiveness of using the sea water as your counterpoise/ground plane....
Depending on your particular school-of-thought, this might be no big deal.....or might be a bad thing....


4) I will no longer get into great long-winded debates about counterpoises/ground planes here on this forum.....


5) In general, I'd recommend using 3" wide copper strap for this 15' run, from your tuner to keel bolts....
And/or...
And/or attach this copper strap to BOTH the keel bolts and other underwater connection points CLOSER to the tuner, such as a bronze thru-hull and/or a shaft strut, etc....if possible....
This copper strapping will cost you a couple dollars per foot....cheaper than 2/0 wire!!!
GEORGIA COPPER - Copper ground strap

GEORGIA COPPER - Comparison of Braid, Strap, Wire


It's not expensive, nor very time consuming.....



I hope this helps...


John
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Old 12-03-2013, 13:30   #65
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

Bill is correct in many of his assessments/observations....but he also has the luck of excellent far field ground conductivity....which goes a LONG way to making the verticals play very well!!!

But, I do agree with him.....string up some wire, and see what you get....a vertical dipole for 20m, strung from a tree is a simple antenna to rig....
(and add a horiz one, up 50' high, as a comparison if you wish...)
Quote:
Originally Posted by btrayfors View Post
These have an extremely low vertical takeoff angle...exactly what you want for DX. They also work very well over land from many locations.

1. 90-95% of the time the vertical dipoles beat the horizontal dipole hands down, and by a wide margin;

2. very rarely signals on the horizontal dipole were almost as strong as on the vertical dipoles; I attributed this to relatively rare high-angle propagation conditions.


A few years ago I put up an end-fed inverted-L antenna. It's about 80-90' long and about 50' high at it's highest point. This has turned out to be a fantastic antenna. I can work all bands with it (and a Palstar AT1KM tuner) and religiously get "fantastic" signal reports on the 40m band which I work every day.

Try it. Throw up a cheap temporary one, made of any kind of insulated wire. I use THHN 10-guage stranded, found at Home Depot. That's robust enough to last for years in a land station setup.


Fair winds....
(gotta go)

John
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Old 12-03-2013, 14:13   #66
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

John and Bill,

Your past input has got me doing research like a mad man. I have discovered my ground conductivity for my area is a 2, so low angle with a vertical won't fly. I measured the length of the crown of my roof on the 2nd story and it happens to be 65'. That got me interested in a quad loop for 75 meters, supported at the crown by (2) 50' fiberglass telescoping masts 65' apart, fed by the coulper at the center of the base leg for a horizontal configuration. The base leg will be 25' above ground, the top horizontal leg will be 90' off the ground and will have a clear 360 degree view as I live on top of a ridge. From all the reading I've done, the lower leg will have a high angle of radiation, thus giving good short hop signals and the top leg being 90' above ground should give good medium distance hops as it has a lower angle of radiation at that height. A good feature I would think if I was a net control station.

This loop will have 260' of wire, and since for the month of March SGC has reduced their SG-235 $305, to $995, I think I'll use it instead of the SG-230. I've looked at the owner's manuals for both and even though they say both are good for mobile, maritime, and base, for some reason they recommend longer wire lengths for the 500 watt SG-235. I wonder why that is?

I'm getting too old to be erecting antennas in scary positions like the crown of my roof. I really want this to play well, making the expense and effort worth it. I miss HAM radio, and as a shut in caring for my dad I look forward to the social aspect of getting active again but don't want a lot of trial and error getting up a decent, all HF band antenna and automatic coulper. This is the main reason for the auto coulper feeding a single antenna for all bands.
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Old 12-03-2013, 15:08   #67
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

To give you well versed HF folks a better understanding of my location, for VHF it has allowed working repeaters that serve Reno and western Nevada to the east, Oregon border and Ashland to the north, SF Bay area to the west, and a few Southern California repeaters to the south. I have very poor ground conductivity for HF, so I think horizontal will be better for me, and the reduced man made noise is nice. Below is my location, from what you can see and knowing of the poor ground, what would be your choice for a single HF antenna that with the auto coulper, work all HF bands.






The home is built on a east facing slope. East being the right side of this picture. Those 50' fiberglass telescoping mast will be mounted to the highest part of the upstairs roof.

This is the west side of the home and since it is on the up slope of the hill, is a single story.

On the southwest side looking north.
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Old 12-03-2013, 15:42   #68
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

Bob,
1) Just FYI...."poor" grd conductivity doesn't rule out a vertical, it just means that it isn't going to play as well as those with "vry good" grd conductivity will....
And, to be blunt, any antenna is better than no antenna, so go with something simple to start with, and grow your antenna farm from there...
With a couple acres and some decent trees, you're the envy of many of those with city lots!!!
Quote:
Originally Posted by deckofficer View Post
I have very poor ground conductivity for HF, so I think horizontal will be better for me, and the reduced man made noise is nice.
2) Don't sweat the "man-made-noise" issue....in my experience it's over-blown....
Besides, most "noise" you're going to hear out in the area you are in, is going to be mainly "natural" noise....and what little man-made noise you might find to be an issue, will most probably be coming from your own house....just like on our boats!!!







2) As I wrote earlier, I'm a fan of big loops....
Quote:
Originally Posted by deckofficer View Post
....from what you can see and knowing of the poor ground, what would be your choice for a single HF antenna that with the auto coulper, work all HF bands.
a) For an easy-peasy "all-band" antenna that actually works and is an easy match to a tuner, etc....String up a big horizontal loop, as high as you can get it (thru / over the trees....use a sling-shot, or bow/arrow), of any shape....make it approx. one-wavelength at your lowest operating freq, and place your remote tuner at the feed point (one end to the "ant" terminal and one end to the "grd" terminal)....
If you can get it up 50' - 60', it'll be a GREAT antenna!! and even if can't get it that high, it'll still work well for you....
{Understand that just like there is no "perfect boat", there is no "perfect antenna", especially one that covers 3-30mhz and is cheap and easy.....but a large horz loop can be a one antenna "antenna farm"....but remember it's not "perfect"!!!}




b) String up a couple slopers (sloping vertical dipoles), for the bands and azimuths you desire.....




That's the best advice I can manage for now....
Good luck...


John
s/v Annie Laurie


p.s.
Years ago, I built a 2-ele, full-size, right-angle delta loop array for 75m....
My friend (now passed) had a 120' tower (w/ a couple yagi's on top) and 5 acres.....I used huge 4" dia and 3.5" dia alum pipes as the top boom 42' long, at 120' high...with the bottom wire about 60'.....making apex at about 1/2-wave high, and the array center at 3/8-wave high....pointed NW'erly out of central FL, with a 70* - 75* half-power beamwidth....it played REAL well all over the US....
But, those were not my $$$$ paying for tower, yagi's, 80m boom, etc....
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Old 12-03-2013, 16:30   #69
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

Quote:
Originally Posted by ka4wja View Post
Bob,








2) As I wrote earlier, I'm a fan of big loops....
a) For an easy-peasy "all-band" antenna that actually works and is an easy match to a tuner, etc....String up a big horizontal loop, as high as you can get it (thru / over the trees....use a sling-shot, or bow/arrow), of any shape....make it approx. one-wavelength at your lowest operating freq, and place your remote tuner at the feed point (one end to the "ant" terminal and one end to the "grd" terminal)....
If you can get it up 50' - 60', it'll be a GREAT antenna!! and even if can't get it that high, it'll still work well for you....
{Understand that just like there is no "perfect boat", there is no "perfect antenna", especially one that covers 3-30mhz and is cheap and easy.....but a large horz loop can be a one antenna "antenna farm"....but remember it's not "perfect"!!!}







John
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p.s.
Years ago, I built a 2-ele, full-size, right-angle delta loop array for 75m....
My friend (now passed) had a 120' tower (w/ a couple yagi's on top) and 5 acres.....I used huge 4" dia and 3.5" dia alum pipes as the top boom 42' long, at 120' high...with the bottom wire about 60'.....making apex at about 1/2-wave high, and the array center at 3/8-wave high....pointed NW'erly out of central FL, with a 70* - 75* half-power beamwidth....it played REAL well all over the US....
But, those were not my $$$$ paying for tower, yagi's, 80m boom, etc....
Thanks John, ordering all the pieces today. The quad loop supported at the highest part of my roof by those 50' glass masts is as high as I can get it, so that is the plan. Lower horizontal leg 25' above ground and upper leg 90' above ground should play well.

As soon as I'm up and running I'll come back to this thread and set up a sked with you to evaluate the loop's performance to your location.

I know you don't think much of my AL-500, but doesn't it need to be at least clean enough for Amateur use? I never use it unless needed as per the rules, and I never over drive it and make sure my ALC is operating properly. Since SGC has that sale on the SG-235, I'm going that route. Here is a picture of my very modest station, just setting on the stair landing waiting to be set up after bringing it up from my SoCal residence that I never got around to setting it up there. That home down there is in the bottom of a canyon, that is why I didn't bother to set it up.

I know it is all old equipment, but at least not as old as my FT-101 E that I still have, or the Icom IC-730 that came out of the boat, or my 1st solid state HF rig, an Atlas 210 that I no longer have.
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Old 12-03-2013, 19:38   #70
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

Back to the SG-230 because the SG-235 won't tune 160 meters without at least 300' of wire. I'd rather give up 4 db of transmit power than lose 160 meters. Plus it saves $500.
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Old 12-03-2013, 21:10   #71
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

Bob -

When an monopole antenna is less than 1/4 wavelength for a frequency in question, the antenna tuner has to add series inductance to make the match. Shorter the antenna, the more inductance required. These coils have to be larger in higher power ATUs to handle the increased current. To maintain a reasonable ATU size and cost I imagine they forgo the biggest inductor(s) and increase the minimum antenna length the higher power tuner will work with. This naturally has the biggest impact on the lower frequency bands. It actually isn't limited only to wavelengths below 1/4 - but that is usually where the challenge is greatest. Looks like you are running into the same type of problem with the loop.

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Old 12-03-2013, 21:36   #72
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

Chip,

I thought it was something like that, makes perfect sense. How often does one get to operate 160 meters with a quad loop that is only 1/2 as big as it needs to be? Like I said, I'll give up 4 db to see how well I can do on the basement band. Last time I worked 160 I was surprised how many old timers were hanging there operating AM. That kind of duty cycle I'm not going to run over 40 watts.
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Old 13-03-2013, 06:02   #73
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

Bob,
I wrote a detailed response here last night, but it was wiped out when I tried to submit it as I had internet connection issues....
So, here's a brief version...
Quote:
Originally Posted by deckofficer View Post
I know you don't think much of my AL-500, but doesn't it need to be at least clean enough for Amateur use? I never use it unless needed as per the rules, and I never over drive it and make sure my ALC is operating properly.
It's operating it on battery voltages (11 - 12.5vdc) rather than 14 - 15vdc, and/or overdriving it in order to get "500 watts or more", that produces the truly horrible IMD products.....
So, if you run it at 14.5vdc, and keep your drive to 20 - 25 watts, it's not too bad....(although I'd still prefer a tube amp...

So, I think you'll be fine with the AL-500 there at home on the power supply, etc....



{Just some info, for those who may not realize it.....there are NO in-band spurious emission specs / IMD specs, for amateur radio gear!!
Yes, harmonic and out-of-band spur specs....but the reason there is NO in-band / close-in IMD spec, is that the amateur radio operator is REQUIRED to manage their transmitted signal within the rules, no matter what transmitter (amp, etc.) they are using, whether they built it themselves or paid $10,000 for it, the licensed amateur radio operator is the one responsible for controlling the transmitter's output in accordance with the rules, NOT the manufactured specs of the radio!!!

These rules state quite directly what is to be controlled.....here are just a few...
Use the minimum power necessary to maintain your communications...
Use no more bandwidth than necessary for the mode (voice or digital) of operation....(FCC recognizes 2.8 - 3.0khz for SSB and 6khz or less for AM DSB, for the amateur radio service, by their rulings and engineering comments, but do NOT specify exact numbers in Part 97...)
Do not cause interference to other amateur radio stations (nor other radio services)....
Maintain your transmitted energy within the band and sub-band, that you (and that specific mode of operation) is authorized for....
Operate your station/transmitter using good engineering and good amateur practice.....

Anyone who reads the ridiculous IMD specs of some of the "modern" ham HF rigs (some have specs of -22db to -24db), will realize that the manufactures have little interest in keeping the ham bands "clean"....
And, it becomes clear that many of today's (last 20 some years) radios are 10db - 20db worse in IMD transmit performance vs. those made 30, 40, or 50 years ago....(that's "progress" for ya')
And further, that these "new, high-tech" ham radios would never meet the stringent commercial/maritime/aviation specs (such as Part 80).....

Understand that the horrible specs of these "modern" radios are with them being operated properly, inside the ham bands.....NOT being mis-adjusted, NOR mis-tuned, NOR outside the bands they were designed/tuned for....so, things get worse when you get the "all knobs at max" operator at the switch...

So, maybe others will understand why, when someone on here (like me) recommends using only commercial/maritime radios on the maritime bands/freqs, and NOT ham radios "opened up", it IS good advice... }

And, if some ham has a transmitter with poor IMD specs, and then adds an external amp (even a "clean" one) things get worse....and if the amp isn't the best, you end up in IMD hell...






The 210x/215x are in my top 10 list of favorite rigs, of all time....
Quote:
Originally Posted by deckofficer View Post
....my 1st solid state HF rig, an Atlas 210 that I no longer have.
It has a great little receiver, even better than many "modern" rigs!!!





I hope this helps some.....

John
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Old 13-03-2013, 09:36   #74
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Re: Do you want an HF antenna that performs 20~40 db better than a back stay ?

John,

Now that I'm back to the SG-230 because the SG-235 won't tune 160 meters on my 260' of loop, no chance of over driving anything. I'll set up the radio for a max out of 20 watts on voice peaks, so that if I need more by switching on the AL-500, it won't put out but 200 watts, what the auto coulper is rated at. Both radio and amp have their own power supply.
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USCG Unlimited Tonnage Open Ocean (CMA)
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