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Benbow
25-05-04, 15:56
Dear Folks,

What is the recommended wire to connect my insulated backstay to my AT-120 tuner ? I see references to GTO15 for this purpose in American publications, but no-one here in the UK seems to know what GTO15 is. Could someone please suggest an equivalent, or at least a description !

Thanks for your help.

Steve


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steve_cronin
25-05-04, 16:33
I think that it is old style (before carbon string) petrol engine ignition cable but if you're only receiving, is it very critical?

Steve cronin



<hr width=100% size=1>The above is, like any other post here, only a personal opinion

Benbow
25-05-04, 17:06
I am also transmitting.

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jerryat
25-05-04, 17:58
Hi Benbow!!

I have just answered this question on this page a little further down!! The thread is headed 'Pactor II/III modem for SSB'

Hope this helps you.

Good sailing!

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Talbot
25-05-04, 17:59
I would give the folks at <A target="_blank" HREF=http://www.sailcom.co.uk/>Sailcom</A> a call - they have beeen very helpful to me.

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Danthegorrila
03-06-04, 11:43
Hi I had a lot of help from yachtcom and from Kiel radio, who supplied the correct cable but I found getting an attachment to the back stay impossible.

I made one by using a bit of copper pipe about four inches long and split length ways. I then cleaned it up very throughly and soldered the end of the cable to it ensuring the cable was touching all the way along with no gaps at all as Im told they are bad. Then the whole thing was fastened to the back stay with four jubilee clips, cable end up to stop water running in. I also made some plywood spaces to keep the cable off the back stay until above the insulator. A bit of old gas hose fits over the cable from the attachment to make a nice arch from the back stay.

I hope that helps, mines worked for over a year.

Im equally puzzled about weather fax frequencies, does not make any sense to me, it works ok for Uk forcasts as I was told the frequencies to use but for staitions in the med Im not getting anywhere, the answer you had may help.

cheers

pete

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Roberto
03-06-04, 14:01
you could also take a suitable length of coax cable like RG58 or better RG8, strip away all the outer braid and just keep the insulator covered internal wire, it will be ok for the purpose



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03-06-04, 17:52

Talbot
03-06-04, 21:07
I was amazed when I read that you had been advised that the ATU should be sited near the radio, and not the aerial itself. This is in total contradiction to all the advice I have been given. btw which SSB, and which ATU? what size ground plates have you fitted?

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03-06-04, 22:01

Strathglass
04-06-04, 06:23
Brian,
I think that Icom probably state that the ATU should be as near the backstay as possible. The reason for this is that any wiring between the ATU and the backstay forms part of the radiating/receiving element and will be live when transmitting.

The purpose of the ATU is to modify the (usually high)impedence at the end of the backstay to aproximately the 50 ohms required by the output of the SSB set to enable it to generate the maximum power and to maximise reception.
A longer length of coax between the SSB set and the ATU will have a minimal effect at HF frequencies once the ATU has tuned itself in.
For the lead between an ATU and a backstay a very good material is the inner core from a piece of very heavy duty coax. But remember that it will be live when transmitting and keep it as short as possible.

I am envious of your trip. I will be ordering my backstay insulators today so have a bit to go yet.

Iain

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Roberto
04-06-04, 07:39
agree with what others have said: keep the distance between ATU and antenna to a minimum, whereas between the radio and the ATU you have much more latitude, a few meters more or less will not make any difference


**Another question for someone - am I allowed to glue the copper tape to the bilges? Can you in fact buy self adhesive copper tape? Could I glass over the copper tape to protect it?**
yes no problem for the installation, besides the copper will not turn greenish, or will anyway but much slower


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Talbot
04-06-04, 09:02
When I discussed the groundplate requirements at length with an expert, he said that for most applications a single 12" xIIRC 4" was the normal groundplate, but this would not be optimised for the lower frequencies, andd thus range at the lower frequencies would be less than optimum. He recommended that I fit 2 of these really big ones on the basis that this would be the best for 2182 khz.

I have a M700(UK) which I plan to fit this winter, but have yet to get the ATU. I had considered trying to get a modem for email, but have been advised that it wont work very well with this radio, and in any case the price of the modem and a years subscription is not very different from an iridium phone. As regards the length of coax, I dont know the answer, but mine will be about 3 metres.

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mdrifter
05-06-04, 17:55
Hi, GTO15 is tinned and shouldn't rot...untinned copper core from co-ax will. Keep the length of "gto15" as short as possible and have the lower insulator as close to deck, e.g. just above rigging screw and as close to the atu. Attach gto15 to atu with crimped & soldered ring terminal; use another ring terminal at other end of gto15 and clamp to ferrule of insulator using jubilee clip with ring terminal pointing downwards to minimise ingress of moisture and wrap with self-amalgamating tape. Have bottom 2-3m of backstay enshrouded to minimise rf burn...If you're in Florida getting gto15 should be easy and "inexpensive". If you have keel bolts you could always tap one and attach copper strap to it thus improving ground. SGC have a great manual for fitting ssb, antennae, etc. on site @ www.sgcworld.com - and their sgc230 atu is a world beater! btw is the Icom atu to feed a long wire...some have co-ax terminals at both ends and might not be suitable for long wire such as backstay - however, you could always rig a dipole...

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