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[Articles Home]  [Add Article]  

Low-Cost One-Touch Tune for LDG AT-897

Jim Schropp (K4SCH) on April 17, 2004
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Easy to build inexpensive alternative to the W4RT One Touch Tune Interface for the LDG AT-897

I recently decided to buy an LDG AT-897 auto tuner to go along with my new Yaesu FT-897 radio and found that while it is a great auto tuner at a great price you really do want to be able to have the One Touch Tune Feature enabled so you don't have to manually change modes every time you want to tune up in a different part of the band.

So thus begin my search for a way to do this without spending an additional $65.00 on a W4RT OTT module. I had also heard the the W4RT module was a bit bulky and the connectors had to be filed down somewhat to make them fit properly. So in search of a solution to my problem the first place I looked was the trusty FT-897 Group on Yahoo.com. (If you own an 897 and aren't a member of this group, JOIN you wont regret it; you will find a wealth of information and a lot of friendly people willing to help you with your problems).

Unfortunately I did not find anything there in the archives that would help, so plan B was to start looking in the FT-897 manual for a way to force the rig into transmit mode with a steady CW carrier. And wouldn't you know it, the ACC jack on the radio has just such a provision built in. By shorting one pin of the connector to ground the rig would go into transmit mode with a steady CW carrier for tuning.

The next step was to figure out A: What type of plug would the AT-897 OTT port take. Obviously it was a 1/8th inch plug, but a mono variety or stereo? It turns out the answer was stereo. Question B: What is the pinout of the AT-897 and does it provide a ground or closure when it wants the radio to transmit? After a little experimenting, the pinout turned out to be pins 1 and 3 were grounded when the tuner wanted the radio to transmit. After determining that, all that was left to do was to build a cable and see if it would work and sure enough it works like a charm.

So save $65 bucks and go to radio shack you can build this for under $10 dollars even less if you have the stuff laying around the shack already. Please refer to the following picture and schematic for detailed instructions on how to build you own low cost One Touch Tune control cable.

73 de K4SCH

Jim Schropp

While I dont personally have a Z100 tuner I have been told that this cable will also work on it as well. Also the FT-857 has the same provision built into its ACC jack so you should be able to use it with that radio as well.

LDG AT-897 Alternate OTT.JPG (50635 bytes)

OTT AT-897 Schematic.jpg (26897 bytes)

Member Comments:
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Low-Cost One-Touch Tune for LDG AT-897  
by K0BG on April 17, 2004 Mail this to a friend!
I found the same thing out about the Icom tuner modual. It sells for about $50 and I built one for less than $10. The only thing I had to buy was the molex plug from Radio Shack. Necessity is the mother of invention. Good Go!

Alan, KBG
 
Low-Cost One-Touch Tune for LDG AT-897  
by K2WO on April 17, 2004 Mail this to a friend!
Thanks for the great insight and the tip. I am using this set-up with a Z-100 with both an FT-897 and a FT-857. It works great! Thanks much!
 
RE: Low-Cost One-Touch Tune for LDG AT-897  
by K2GW on April 19, 2004 Mail this to a friend!
Thanks for the insight as to how the jacks work on the AT-897. But does your patch cord also work in SSB or just CW, AM, FM and RTTY modes?

I can see how it can trigger the transmitter to be key down during CW tune, but the W4RT OTT module also switches the FT-897 to digital mode momentarily to provide carrier during the tuning cycle and then back to your operating mode aftewards. That's what the the little chip and connections to the CAT jacks on the AT-897 and FT-897 do in that OTT set-up.

So I guess as long as you also switch mode from USB to CW before and then back after the AT-897 tune button, your patch cord would work. But in SSB mode , isn't it then more correctly called "three touch tune" ?

Thanks & 73

Gary, K2GW

 
Low-Cost One-Touch Tune for LDG AT-897  
by NM7H on April 19, 2004 Mail this to a friend!
I have done this with my LDG Z100 and FT857. It does not matter what mode you are in, it automatically sends out a carrier. Only problem is it is full power, or whatever power you have your radio set to. Otherwise it works pretty slick.
 
RE: Low-Cost One-Touch Tune for LDG AT-897  
by K4SCH on April 19, 2004 Mail this to a friend!
Yes it will provide a cw carrier to tune with not matter what mode you are in. the only draw back is it is full power but as far as I know the W4RT version dosent reduce your power either.

Jim K4SCH
 
RE: Low-Cost One-Touch Tune for LDG AT-897  
by K2GW on April 20, 2004 Mail this to a friend!
Thanks for the info that it does also work in SSB mode! I'll bet Yaesu added that feature internally for etither the ATAS-100/120 or their own tuner.

73

Gary, K2GW
 
RE: Low-Cost One-Touch Tune for LDG AT-897  
by KD5UJX on May 10, 2004 Mail this to a friend!
I don't know if any one is still following this, but, I want to use the Z-100 WITH my High Sierra 1800 to eliminate the "fiddling" with the manual control to tune to less than 1.5:1 SWR so the darn FT-857 won't chop up your signal. Question: can I leave my W4RT in line and use this arrangement to "fine tune" the antenna?
 
RE: Low-Cost One-Touch Tune for LDG AT-897  
by K4SCH on May 10, 2004 Mail this to a friend!
I'm not sure I completely follow what you are trying to say but the interface is designed to replace the W4RT as it does the same thing. Also you can only pulg one interface into your tuner at a time.
 
Low-Cost One-Touch Tune for LDG AT-897  
by N9POA on May 17, 2004 Mail this to a friend!
I picked up a z-100 at Dayton and wired up a cable like this for my Icom 718. Does anyone have a design for a cable that will to the opposite? Force the tuner to tune when the radio wants it to? I'd like to use this tuner as a tuner for my 706 in the vehicle and would like to stuff the tuner out of the way.

N9POA
 
Low-Cost One-Touch Tune for LDG AT-897  
by K6SBA on May 24, 2004 Mail this to a friend!
Hi Jim,
Just bought a new 897D and a Z-100, so you article is very interesting to me. What is that little connector (RJ??) that appears to be spliced into the cable just behind the OTT tuner port plug? It does not seem to appear on the schematic.

Tnx es 73 de K6SBA
David in Santa Barbara CA
 
RE: Low-Cost One-Touch Tune for LDG AT-897  
by SM1NVV on February 16, 2005 Mail this to a friend!
That little thing is an press on connector that you press on after that you split up your cable.
The standard cable is straight on connected, as you see in the schematic you need to switch one side from the tip to the middle ring.
Thats why you need the connector.
Sorry for my english.

73 de SM1NVV Tommy
 
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