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Author Topic: Getting an L-4B to run on a Yeasu 897D  (Read 1488 times)
AB9DF
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Posts: 81




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« on: January 19, 2013, 03:32:09 PM »

Does anyone have any suggestions on hooking up an L-4B to a Yeasu 897D?  I have the amplifier all hooked up and running and only now need to get the amp to trip upon keying the mike.  I do have a Heil foot pedal that trips my mike and it has a RCA plug that used to fit in my old AL-84 that would ground out and cause the amp to open up.  But the Drake amplifier has no such plug on the back.  There is a two pin plug and I expect that this is where I would connect the radio (ground it out and trip the amp to work) upon keying the foot pedal. 

Dont want to get wordy.  Any help would be very helpful

Thanks so much for all your help!
Rob
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K7KBN
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Posts: 2766




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« Reply #1 on: January 19, 2013, 04:03:43 PM »

The manual seems to cover this.  The only two pin jack I see in the picture is labelled VOX RELAY.

If you don't have a copy of the manual, you might get one via Google.  There are a lot of sources, and most of them are free.
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73
Pat K7KBN
CWO4 USNR Ret.
WB2WIK
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Posts: 20547




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« Reply #2 on: January 19, 2013, 05:38:59 PM »

Yep, on the L-4B it is labeled VOX RLY and just shorting those two pins puts the amp into TX mode.

The L-4B complete manual is on line at http://www.wb4hfn.com and elsewhere.
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AD4U
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« Reply #3 on: January 20, 2013, 05:01:22 AM »

I don't think the 897 can short those pins without the typical keying "interface".  Of course you could use your foot switch, but that does not seem to be the best way to do it.

Dick  AD4U
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WB2WIK
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« Reply #4 on: January 21, 2013, 03:09:35 PM »

I don't think the 897 can short those pins without the typical keying "interface".  Of course you could use your foot switch, but that does not seem to be the best way to do it.

Dick  AD4U

The FT-897D amplifier keying circuit is rated +50V and 400mA.

The L-4B definitely falls well below 50V, but I'm not sure about the 400mA.  It would be very easy to measure this by just placing a VOM (on a 0-1A range) across the amplifier VOX keying pins to key the amp.  Doing this should key the amp and at the same time read how much current the relay draws.

If it's <400mA, no need to do anything except connect the rig to the amp via its keying line; if it's >400mA, then a lower current keying interface is required.
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K4FX
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« Reply #5 on: January 24, 2013, 06:27:02 PM »

There is a second place on that rig to key an amp if needed. There is a jumper inside the rig that can be moved to make the ACC jack a send jack. It has ALC on the tip and the ring has, by default, TX Request meaning you can transmit a CW carrier by grounding the ring. Move the jumper and the ring becomes another TX GND, providing the same function as the TX GND in the CAT/TUNER/LIN connector. I have never seen this mentioned in the manual, but rest assured it is there. Like the "relay cleaning" routine, there are a few undocumented tricks in this little rig.

If you don't have one of those mini-DIN connectors it would be a lot easier to move the jumper and use the ACC jack, and a heckuva lot easier to solder than those teeny pins on the mini-DIN.

I am not sure about what the current draw on that amp is, but you could use a little reed relay or the like to key the amp and key the relay with either of the Yaesu's TX GND's to provide peace-of-mind and protection to the rigs keying circuit for just a few bucks, or you could buy an Ameritron buffer for a lot more.

You could just hook up a foot switch to the amp, but I prefer to let the PTT do all the work, one less thing to worry about.

Good luck,

Bill K4FX

PS Mine is a 857D, but the 897 has the same feature, just look for the jumper, it is very close to the ACC jack,

 
« Last Edit: January 24, 2013, 06:31:08 PM by K4FX » Logged
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