Tor
If you can’t find a decent price on an SGC tuner, consider this.

http://www.ldgelectronics.com/c/252/products/1/3/1

This is a nice tuner that runs off 12v and works much the same as the SGC tuner but is more cost competitive ($250). It needs to be mounted in your nav station however. Though its small, it would take up some room and you’ll have to make your own mounting brackets.

This tuner is designed to feed a 50 ohm antenna. To adapt it to a short random wire such as your backstay you need to mount a balun at the base of your backstay. “If you wish to use it with longwires or antennas fed with a balanced transmission line (e.g., ladder line), an external balun is required. The LDG RBA-1:1 balun will work with short random wires and the RBA-1 4:1 balun is suited for longer wires.” These run about $30. I would suggest contacting them to get a recommendation as to which balun would work best.

Best place to buy either is HRO
http://www.hamradio.com/

Regards
Rich KE1EV

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Tor
Its too complicated to explain in a short email. In brief, you need to convert the unbalanced output of your rig to a balanced load otherwise the 50 ohm load point your rig expects wont coincide with a low standing wave ratio (SWR). This is the ratio of power going into your antenna divided by what is reflected back to your radio. Reflected power isn’t going out over the airwaves. Instead it heats up the feed line. An SWR of 1.0 is ideal, but anything below 1.6 is usually considered good enough. There are a lot of ways to do this, but a small transformer or inductor is what is typically used. You can make something yourself by just coiling some feed line to form an inductive load, but that’s too involved. The LDG autotuner will switch in inductive and capacitive components to adjust the feed impedance to your radio so that it sees a 50 ohm load. That’s what your radio is designed for. The SGC does the same kind of thing. Since you only have a couple of weeks to sort this out, I suggest calling LDG and discussing your needs. They have been very helpful in the past.

The LDG tuner is fully automatic like the SGC, but its not in a watertight case. You need to mount it someplace dry. It has frontpanel indicators that you’ll want to see too. It has frontpanel controls that can be used. The SGC tuner will cycle until it gets an SWR less than about 1.6. If it can’t get that low it doesn’t give up. It keeps cycling. This can be a disadvantage since there may be frequencies at which you can’t get an SWR quite that low. Maybe 1.8 is the best you can get. The LDG tuner can be hand tuned using the frontpanel controls. You may not have the skills to determine how and when you’d want to do this so it may not be a feature you’ll need.

Consider the SGC tuner to be a mindless appliance for people who don’t want to know how things work. Its rugged and expensive.

The SGC tuner is more flexible and less expensive. It must be mounted in a dry place because its not rugged. Since it isn’t designed for a longwire antenna, it needs to have a load matching network mounted near the base of the backstay. The load matching network is called a balun. I would consider the backstay to be a short “longwire” antenna.

Hope this helps
Rich

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Tor
If you decide to go with the LDG tuner, they make three models, the AT-100, AT-200, and AT-1000. These indicate the power rating of their tuner, 100, 200, and 1000 watts. Some marine SSB radios are rated for 150W, so the AT-200 would be a good choice. I have an AT-100 at home in my “shack”, and I have an SGC-230 on my boat. If I buy another tuner for home, it will be an AT-1000.

Here’s my shack.
http://www.richardcarter.net/radio/

Rich

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Tor
I’m not sure that the LDG tuner has the same range of tuning that the SGC tuner provides. Its a much smaller tuner and probably has a more limited tuning range. This would limit the amount of correction that the tuner can make and might prevent you from getting on some bands. SGC doesn’t publish their tuning range. If you call LDG, you might want to ask them if this tuner will be adequate for your backstay. I’ve talked to them in the past. I think they will be honest. Knowing the length of your backstay between the insulators would help.

Rich

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