HF-SSB cable routing

[transmitterdan]

Originally Posted by S/V Illusion

Are you serious?

It’s a spell check thing. Lighten up...and try reading all the way to the end of the thread before jumping in.

[alctel]

Originally Posted by ka4wja

The short answer is, no...not much difference...
The long answer is, the "standard AWG wire" is actually your antenna, just as much as the covered lifeline wire is....and actually even more so, and the high-current point of the antenna (which will be the lower end / bottom end, for the lower freqs bands) is where most of the radiation occurs...

So, please remember that the remote tuner IS part of your antenna, as is the wire leaving the tuner, whether it is GTO-15, or any other wire....it IS your antenna, and should be dealt with as such..


Gotta go..

John

Oh yeah I get that - so I should be using GTO-15...?

The tuner is as close to the base of the antenna as I can get - the wire run is only around 1 foot inside the boat.

Asking cos my autopilot goes nuts whenever I transmit on 40 meters or higher frequency, despite me ferriting the crap out of everything and installing a line isolator.

[transmitterdan]

Yes, GTO-15 from the tuner to the "antenna" is SOP. The antenna begins at the bolt on the tuner. So the wire is the very first part of the antenna. If you can't find GTO-15 then a reasonable substitute is a piece of coax with the outer insulation and braid removed.

As to your autopilot, how does it go nuts? If it can't hold a heading then the electronic compass is probable the culprit. If it goes into standby or some error mode then there is a different problem. Getting the ground return to the water with as short a run as possible will usually help. A long run of strap from the ground stud on the tuner to the underwater metal can cause a lot of issues like this. That so-called ground connection is also part of the radiating antenna but most people don't think of it as such.

One thing that bites some installations is the DC power feeding the transceiver. In transmit as much as 25A of current are used. The SSB is often second behind a windlass in current draw. Powering these high current devices is best done with direct from the battery wiring. Many boats power the SSB from a distribution panel that also powers electronics like the AP. But the SSB can cause voltage spikes on the DC bus and that can drive electronics nuts. Also, the DC wiring can create a magnetic field that deviates the electronic compass causing the autopilot to turn off course during transmit. The DC wires for high current devices should be run with the + & - wires kept very close to one another. By doing that the magnetic field is minimized. Twisting the +&- wires together will truly eliminate the stray magnetic field.

[ka4wja]

alctel,
transmitterdan answered your specific question on your autopilot issue....and until we have more details from you, there's not much else to add...

Also, with only "1 foot" of wire inside your boat from your tuner to the backstay, there is almost certainly no issue there....and no need for concern over not using GTO-15 wire...
But, there are a few other important things to mention...

Originally Posted by alctel

Oh yeah I get that - so I should be using GTO-15...?

The tuner is as close to the base of the antenna as I can get - the wire run is only around 1 foot inside the boat.

Asking cos my autopilot goes nuts whenever I transmit on 40 meters or higher frequency, despite me ferriting the crap out of everything and installing a line isolator.

Generic answer about GTO-15 wire:
GTO-15 wire is a 14ga stranded-tinned-copper wire with a thick/tough high-voltage insulation (rated at 15,000 volts breakdown) and a UV-stable outer jacket....

This is a good choice for end-fed antennas, as the RF voltage, on some freqs, can be quite high (several thousand volts) at the feed point....and being a tinned copper wire it is also a good choice for our marine environment...

It is not "magic"....i.e. it does not increase your radio's signal, nor reduce your RFI, etc...(except in cases where you'd have RF-voltage flash-over, or corrosion issues, it is not a super critical item...)
But, fyi, due to its high-voltage properties it can be reliably secured to the lower end of a backstay, or fed thru a deck fitting, etc. without worry about arcing / shorting-out...other than this, and its corrosion resistance, it's doubtful it would ever improve anyone's system versus using "a regular piece of wire"....
BUT...


What is critical in your question are your words differentiating your "backstay" and your "wire"....writing what you have, is very common, so no worriers....

Important part of this posting starts here:

But, everyone should understand that their HF antenna starts at the tuner....actually the tuner is part of your antenna, the coils and caps inside are darn important, along with the wire leaving the top of the tuner, this is the first part of your antenna!!


What is even more important is how important this "first part" of your antenna is....without getting into "antenna theory", just please understand that the "high-current-point" of an antenna is where most of its radiation occurs....
And, on the lower HF bands (2mhz, 4mhz, and 6mhz marine...and 160m, 75m/80m, and 60m ham) the high-current point of our typical 40' - 45' long backstay antennas is right there at the tuner output / at the top of the tuner (or within the first 4' to 5' of this "wire")...
On the lower-middle HF bands (8mhz marine and 40m ham) the high current point is typically only a few feet further up the wire, some times at deck level or just above the deck....

Of course, on the higher bands (12mhz, 16mhz marine...20m, 17m, 15m, etc. ham) the high-current point of a typical 40' - 45' backstay is well up in the air and clear of other "stuff" on-board...BUT...

But, for those with shorter backstay antennas, or those with the typical 23' whip, the high-current point is right there at the top of the tuner on all the lower and lower-middle bands (all freqs below 10mhz)....and only a few feet up the wire on 12mhz, and a few feet up the 23' whip on 14mhz/20m ham....

Again, without delving into antenna current theory, etc....suffice to say that this can be an issue with some installs....
But, of course we are all on boats.....and their purpose is not to be antenna platforms, but rather forms of transportation, recreation, etc....in effect our backstay antennas must first hold up the mast....and well down the list of their purpose is to be a good antenna....so, we should all remember that....and then...

And then....we can look at how to better design / implement our HF antennas...

In my opinion, making sure the "high current point" of your antenna is as much in the clear and as far away from anything that reduces its effectiveness in radiating your transmit signal into the atmosphere, as possible....as well as removed, as far away as possible from RFI sources on-board....but, of course, these are boats, and they're darn small (in terms of wavelength of HF signals), so there is only so much we can do....

But, what we can all do is remember that our antennas start right at the tuner....and the most important part of our antennas, is the very first part / the first few feet!! And, here is where we should not fall-short of striving to optimize things....

In my opinion, we should all strive to not differentiate between the "backstay antenna" and the "wire" leaving the tuner....they are BOTH part of the antenna....and in many of our communications bands, the "wire" leaving the tuner (and its placement) is a very important part of our antenna!!


BTW, transmitterdan gave some excellent input / advice here....please heed this advice!! I'm just adding some frosting to the cake!!

Fair winds.

John

[S/V Illusion]

Originally Posted by transmitterdan

It’s a spell check thing. Lighten up...and try reading all the way to the end of the thread before jumping in.

I did. Must be a pretty fancy spell check to change the meaning.

[alctel]

Thanks for the info guys, great stuff - though it kind of deepens the mystery!

I don't get *any* interference problems on 2/4 and even 5Mhz - it seems to be on 7mhz and above, it being worse the higher you go - but this makes little sense as with a ~40' antenna the higher bands should have a higher current point and therefore further away from the autopilot etc! (it also sets off my propane alarm but I deal with that by turning off the propane system before I transmit - I had a problem with it setting off my standalone carbon monoxide sensor as well but i moved it to the other side of the cabin and it's fine now)

The radio is plugged directly to the batteries (though it does go through the amperage shunt) not through a bus bar.

When I say the AP goes nuts, I mean it loses connection to the AP computer. I'm wondering if it's the N2K network shorting out rather than the actual AP. It comes back almost instantly.

[ka4wja]

Oppss..
Sorry for the confusion...

My comments regarding the importance of knowing where your antenna starts from...and understanding where it radiates most of your transmit energy....were not meant to be comment / advice about your autopilot-transmitter interference!!
These were generic about our "antennas" (multi-octave, end-fed, verticals)!

Sorry about that....


To be clear, your "transmit RFI" / autopilot interference probably has nothing at all to do with where the high-current point of your antenna is, on 40m...

Without being there, and seeing the install....it's difficult to know how/why/where the problem is being caused....

But, simply wire the radio directly to the batteries....no shunt, no bus-bar (and use adequate sized wire)....just doing this can help....and it is easy-peasy and cheap!!

In addition to the DC power connection for the radio...here are some other best guesses...
1) Antenna ground / RF ground issues??
You mention you use only 1 foot of wire from tuner to backstay, so thinking you may have a rather long and/or uncommon / complex routing of an antenna ground??
Do you have a short / low-impedance direct sea water antenna ground??

Being that your issues is more prominent on the higher bands, where length of ground connections becomes more critical...I'm suspecting something not optimized in the ground system??



2) Unfortunate resonance (on 40m and/or other bands...as some are of course harmonically-related) of your autopilot wiring (either or / or all...control cabling, power cabling, drive cabling, fluxgate/compass wiring, rudder-position wiring, etc...)
BTW, I had a GFI electrical outlet that "chattered" when I transmitted on 6mhz....I changed it out to a new one, and never had the problem again....was it some weird resonance of some AC electrical wiring on-board, on 6mhz?? was it a "faulty" GFI outlet?? was it both?? was it antenna ground related?? (I don't know the answer to those questions, but my guess is the answer is "yes" to all of them...)


3) Antenna tuner (and antenna) proximity to autopilot (corepak, and/or control head, drive, fluzgate, sensors, etc..)


4) NMEA 2000 network wiring issues....poor connections, poor/missing shielding (your NMEA network wiring is shielded, yes???)...
Remember shielding of cables must be connected to chassis ground of the devices at BOTH ends, in order to have any RF-tightness / effectiveness, no matter what some internet-yahoos claim about connecting shielding at only one end (of course their actual problem was poor ground or ground loops, so lifting the shield solved their issue, but it wasn't RF ingress to begin with, so their whole point is moot...


5) There could be many other issues that could all be working together to cause this....and I'd need to be there to see / examine things personally to get a better idea....
Not the least of which is that some radios have notorious case emissions, other radiation issues, etc. that makes them poor in a close-proximity environ with other devices....(the Icom IC-7200 and the SGC-2000, are two that come to mind....but some other ham rigs have these issues too)
Of course there are some electronics that are a bit more susceptible than others, too...


6) BTW, ferrites (especially just clamping on a few) are NOT always effective....especially if you're just buying generic ones, rather than those designed/sold to work best on HF freqs...(mix 31)

Originally Posted by alctel

Thanks for the info guys, great stuff - though it kind of deepens the mystery!

I don't get *any* interference problems on 2/4 and even 5Mhz - it seems to be on 7mhz and above, it being worse the higher you go - but this makes little sense as with a ~40' antenna the higher bands should have a higher current point and therefore further away from the autopilot etc! (it also sets off my propane alarm but I deal with that by turning off the propane system before I transmit - I had a problem with it setting off my standalone carbon monoxide sensor as well but i moved it to the other side of the cabin and it's fine now)

The radio is plugged directly to the batteries (though it does go through the amperage shunt) not through a bus bar.

When I say the AP goes nuts, I mean it loses connection to the AP computer. I'm wondering if it's the N2K network shorting out rather than the actual AP. It comes back almost instantly.

Finally, on a 36' boat, everything is pretty darn close to everything else....so, you might find yourself working in God's little acre ("between a rock and a hard place")....so..
So, good luck...



Fair winds

John

[alctel]

Thanks for taking the time to type that out! Will go through carefully and recheck everything.

I have a KISS ground currently.... (I know, I know) but could change that to a seacock run pretty easily. Just paranoid about stray currents melting it!

[transmitterdan]

Check that all the NMEA cables have an intact shield. There should be no breaks in the shield at TEE junctions or other connection points.

If the NMEA cable shield is “grounded” someplace other than equipment consider removing that ground and see what happens. Some people think that is a few ground points are good then lot of them is “better”. That isn’t always the case.

If the NMEA data rate for your network is programmable consider lowering the data rate speed. As long as there is enough bandwidth to carry all the traffic extra capacity doesn’t help and it makes the system more sensitive to noise. Some systems only work at one rate so this may not apply to your system.

Ferrites on the NMEA cable right at the AP computer might help.

[transmitterdan]

The KISS “ground system” is not a ground system. The wires in that bundle radiate RF. Try to put that bundle well away from any electronics. It could be the cause of your AP problem.