weak power output

Feb 17, 2006
5,274
Lancer 27PS MCB Camp Pendleton KF6BL
My ground strap is attached to the ground lug of the tuner as per the Icom tuner instructions
Bill, he is using the GTO15 cable to connect to his backstay via the chainplate. His RF cable terminates at the antenna tuner input. So the ground of the coax cable between the tuner and the radio hopefully is not radiating anything.

Get, where does the ground strap go from the tuner? What is the ground strap connected to?
 
Nov 26, 2008
1,966
Endeavour 42 Cruisin
I have 2 bronze plates under the hull near the stern.

I ran the ground strap to one plate. My bonding runs to the other.
It was suggested I connect both plates.
When not connected, there is some millivolts between. But a quick test seems to show better power draw with them disconnected. Havent tried to reach out with them disconnected.
But Im concerned about that bit of voltage.
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
I'd recommed you look at some land antenna/tunner/transmitter pictures. NONE of them have the tunner acting as the groundplane for the antenna. Infact the tunner is usually indoors and quite distant from the antenna proper. There is always the need for a ground plane AT THE ANTENNA. The tunner ground is just to keep the coax cable sheath at ground potential so there is no unintended RF inside the radio shack.
The setup you describe would have the full length of the 'wire' from the tunner to the backstay and the backstay as a radiating element. If that has curves and angles in it getting to the backstay you WILL get some pretty weird radiation patterns. Those almost never are aimed at the horizon (which is what you want for long range comms). You might try the NVIS approch and freqs as that is probably what you with your current set up.
Lets be clear as there is a lot of confusion as to what a tunner does. The coax from transmitter to tunner HAS to have a 50 ohm impedience or the transmitter will not be happy. If the antenna does not present a 50 ohm impediance the tunner matches the 50 ohm transmitter side to what ever the antenna actually is at the frequency being used. It does NOT pass the power if there is a mismatch. The transmitter sees 50 ohms and transmits at full (or whatever you pick) power. The power cannot traverse the tunner if the antenna does not present a 50 ohm impediance. 49 ohm and most of the power is transmitted, 300 ohm or 10 ohm and almost no power is transitted, but the transmitter is happy. This does get the maximum power out but I'd hardly call it a "ham savvy" solution. Which is why I'm not a big fan of tunners, better to just make the antenna present 50 ohms.
Start thinking of cutting your backstay to actually be resonate at the freq you use a lot and getting rid of the tunner all together. If you use multiple bands think hamonic (quite a few bands are harmonic of each other) or some sort of gama or delta tuning device.
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Hey Brian
I get that the turanmitter to tunner cable is not tranmitting. The cable going to the antenna from the tunner without a ladder line or coax HAS to be transmitting RF out to the world, or at least trying to. RF cant tell the differance between a plastic coated wire, the chainplate or the backstay. they are just single conductors unless I'm missing something about the GTO15 cable's construction. with no sheath ground (or ladder line type ground)it has to be radiating. kindalike attaching the antenna to the back of the tranmitter and running a single wire out the window and through the yard 50' then up a tree. If you think "just the vertical part" going up the tree is radiating you are kidding yourself.
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
The only thing I can think of is the AT140 is designed to operate in very close proximity to the antenna proper. This would suggest that you keep the GTO15 cable very short and straight AND you keep the tunner ground short and try to locate it as close to "right underneith" the antenna radiating element.
Still think this is not a great solution. I have a 5 watt transmitter and just allagator clamping the center coax wire to the backstay (it is not resonate at my most used freq of 13 MHz BTW) and running a braided wire from the coax sheath to the water gets me south america and europe pretty regularly. The trick is to get the water surface (not deep down) working so the antenna has a GREAT ground plane to push against. IMHO
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Just looked at the AT140 manual and it does have the ground plan (counterpoise) coming out of the tunner. It also suggests that if grounding to the sea directly is not avalable......which tells me :
keep the GTO15 cable short and straight
run the ground (counterpoise) through a thru-hull and into the water for maximum ground plane effectiveness with as short and straight and directly underneath the (in this case) chainplate.
 
Feb 17, 2006
5,274
Lancer 27PS MCB Camp Pendleton KF6BL
Bill, yeah, GTO15 is kind of like sparkplug wire. Have a very heavy insulation around the conductor. I really looks like coax, but there is not outer conductor (I am sure you looked it up and saw that). The GTO15 is part of the antenna. So the total length of the backstay, plus the GTO15, is the antenna. The highest current point is at that piece of GTO15/chainplate.

Get, just for fun, try cutting a radial for the primary frequency you operate on. Attach it to the lug and let it lie around the area of the tuner. If possible, stretch it out but if not, coiled will work also. Here is how I have my setup at home which mimics what I might do on my boat. I have a 36' length of wire as my antenna. Connected to a 4:1 UNUN balun. Connected to that is a current balun to keep the RF from folding back on my coax. Then a length of coax to an autotuner, then the rig. The other side of the 4:1 is a 25' length of wire dropped down and just lying around (kind of like a very very very simple KISS system). That's it. I get out OK enough to make contacts. Not going to win any contest, but good enough.
 
Feb 17, 2006
5,274
Lancer 27PS MCB Camp Pendleton KF6BL
Not to beat a dead horse, but SGC, the manufacture of a fine antenna coupler, suggests using a light bulb. I did this when I was much younger and thought it cool. But forgot all about it until I read it in the SGC-230 Antenna Tuner manual.

http://www.sgcworld.com/Publications/Manuals/230man.pdf

Go to page 38 in the manual (or page 46 in PDF reader) for more info on how to do this. Worth a try.
 

druid

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Apr 22, 2009
837
Ontario 32 Pender Harbour
Total Shot In The Dark here, but this is a problem I have with my Ham SSB: maybe your mike isn't putting out enough audio. In other words, you're not modulating 100%. AM or CW would put out full power, but SSB is dependant on the audio. Make sense?

druid