Pairing Icom ham radio with Sea 1612 Tuner

[cburger]

Our vessel has a SEA 1612 antenna tuner installed. Just purchased a nice used Icom 706 MKII radio. Will it be possible to use tuner with this radio?

[stormalong]

Yes, the 1612b is a carrier driven tuner. I am using one work a Kenwood ham rig. The only tricky part is getting the tuned indication to work. I built a simple circuit to do that about 30 years ago. I don't remember the details but it involved a zener diode and a pull up resistor. PM me and I will dig out the details.

The 1612 is an excellent autotuner.

[Brian.D]

You can also use a RC circuit (resistor and capacitor) to create a timed key on key off. These are very simple to build and test. You might need to manually set the output power to 10 watts or so.

Here is a write up on how to do this. The gear is different but the theory is sound and the same. I have an Icom IC707 and tried it with an MFJ tuner and it worked.

Using a 470uF 16v Capacitor and 100K resistor (in parallel) gives a tune cycle of approximately 8 seconds. A 1000uF capacitor gives a tune cycle of around 15 seconds with the same resistor value.

https://www.qsl.net/g3vgr/706tune.html

[cburger]

Thank you gentleman, this is encouraging.

[Brian.D]

Please let us know how it works out for you. Good info to have.

[flyingnut40]

Following

[Brian.D]

Here is another option. You will have to determine what is the TT (transmit terminate) and what is the TS (transmit stop) on the IC-706(). This uses only a 3.3K 1/4W resistor. It is manual so you will need to push the tune button to start tuning, and again push the tune button to stop tuning. Although this is using a Kenwood TS-50, it MIGHT work on the 706. Might being the operative word.

iz8jji QRP Radio: TS-50 to LDG Z-100 plus connecting cable

[stormalong]

Sorry for not responding sooner. The info on the tuned indicator is on the boat and it will be a few days before I get there to get my notes.

A few things off the top of my head:

This is a carrier driven tuner so all you have to do to tune it is to transmit. I usually just blow into the microphone to get it to tune. My friends always knew it was me tuning up when they heard that. Keep in mind the when transmitting SSB just keying the mike does not transmit - you need to talk or make noise.

Depending on the length of your backstay or whip antenna you may have difficulty tuning up on certain bands. Specifically low frequency bands.

The only thing other than the mod below is the tuned indicator. This needs a simple two or three component circuit to work properly. The SEA 222 that this was designed to work with has a tuned indicator on it. I still have the SEA 222 and put in a switch to power the tuner either from the SEA or the Kenwood.

The documentation that came with my 1612b suggested a resistor change if you are using the tuner on ham bands.

There were three versions of the 1612, versions b and c were improvements but I don't know what the differences are.

These are still serviced by SEA in Mount Lake Terrace, Washington. Not far from where I live.

I will post again when I have the info on the tuned indicator and the mod for ham bands.


Brian
N7BMW

[AA3JY]

Another way to carrier tune the auto tuner is in AM mode..

[Brian.D]

Since it is a 706, it might have FM mode, which is also another way. Am or CM or CW, your choice.

[Pizzazz]

Short answer: connect power and carrier to tuner and use as normal. The tuner will autotune and you do not need to worry about it.

Long answer: there are four connections on the tuner. 12+, ground, demand tune and tuned indicator. If you connect demand tune to ground, it will force the tuner to tune. Hence it is called demand tune. It is useful to wire a switch to do this, so that you can force it to tune. The Tuned connection will go low when it has tuned. You can connect a small solid stay relay to it and then a tuned light. In reality, the tuned indicator is useless, you need the SWR which you can get from the radio.