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Author Topic: Signalink and FT-450 - Can't control TX power (tried 100k resistor, etc.)  (Read 5406 times)
JAKK
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Posts: 14




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« on: December 28, 2011, 12:45:27 AM »

Hi. I recently purchased a Signalink to use with my FT-450 for digital modes. It appears to be interfacing with DMS 780 and my rig okay as I can see the waterfall display and key the rig for transmit, but I can't control the power level via the tx pot on the Signalink- it is always maxed out and the ALC meter is a little over half way on the scale, even with the tx pot turned all the way down. I have added the 100K resistor which replaces the MIC jumper as well as tried enabling JP4.

I have the PTT in DMS 780 set to "none". I am using Windows 7 and have the USB codec volume set to 100% and the DMS 780 volume set to 50% as per the suggestions on Tigertronics' page. I tried playing with the DMS 780 volume, but it did not seem to have any effect at all. There is a clear cutoff between volume level 15 and 16 in Windows, with 15 not keying the rig and 16 keying it. Installing the 100k resistor only seemed to raise this cutoff threshold, it did not allow me to adjust the power/tx level. I know I am probably missing an obvious step, I'm just not sure what it could be given I have tried the 100k resistor and playing with the volume in Windows, and the tx power level is still maxed no matter what. Thanks for your help.
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VA7CPC
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« Reply #1 on: December 28, 2011, 08:59:45 AM »

Yes, the FT-450 has higher sensitivity than it needs for the SignaLink.

If you have a Windows volume control for the USB Codec, don't be afraid to set it down to 5% - 10% -- it won't do any harm.
And the SignaLink "TX" control should be very, very close to the full-CCW setting.

Using digital VOX on the FT-450, you have to accept this rule:

. . . Set menu item "DIG VOX" to 100.

That raises the sensitivity of the DIG VOX amplifier, and puts the rig into XMIT mode at reasonable ("no ALC") drive levels.

You should then be able to use the Windows volume control, along with the SignaLink TX control, to reduce the drive to the rig.  The ALC indication will drop.   And the rig will stay in XMIT mode as the ALC goes down.

You can get down to 10 - 20 watts that way, before the digital VOX turns off.

Once you get it working, you'll find that the FT-450 is a great digital-modes rig.  IMHO, of course.  It could use narrow filters, but its IF DSP isn't quite fast enough to support them.

          Charles
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AG6WT
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« Reply #2 on: December 28, 2011, 09:42:24 AM »

Make sure the RF power setting on the FT-450 is set to 100 (100 watts max output). If you set it too low, you will always see ALC indication regardless of your Tx setting on the Signalink pot.

With RF power set to 100, you can adjust the Tx drive on the Signalink so that you can transmit 30-40 watts without any ALC showing on the meter.
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JAKK
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« Reply #3 on: December 28, 2011, 05:46:01 PM »

Hi. I tried setting dig vox to 100 (it was off before) and setting the USB Audio Codec to 5-10% behavior, but I still see the same binary behavior (either not keyed or keyed with 100% tx power and high ALC). I have the tx knob as far counter clockwise as it can go, the 100k resistor in, and I have tried both with and without the JP4 enabled on the Signalink. I should have the PTT set to "none" in DMS 780, correct? And, if this is working correctly, I should see my tx power start at zero and increase as I turn the tx port on the Signalink clockwise, with my rig's tx power set at max?
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JAKK
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« Reply #4 on: December 29, 2011, 03:42:05 PM »

Got it working-turns out the 450 has to be set on USB/LSB, not "Data" mode.
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VA7CPC
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« Reply #5 on: December 29, 2011, 06:43:13 PM »

If you're plugging into the DATA jack on the back panel of the FT-450, it should be set:

. . . DATA mode;

. . . menu "D TYPE" = USER-U

If you're running into the microphone jack on the front panel, mode USB will work OK.   BUT:

If you're running into the microphone jack, _that_ is why the SignaLink is putting out too much voltage for the rig!   You should set MIC GAIN to LOW -- and if you're lucky, you'll be able to reduce audio drive enough to get no ALC.

       Charles

PS -- Usually, I don't argue with a working setup.  But there are good reasons for going into the rear-panel DATA jack, rather than the MIC input.
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W8JX
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« Reply #6 on: December 30, 2011, 07:26:53 AM »

there are good reasons for going into the rear-panel DATA jack, rather than the MIC input.

Yes indeed yet many still try to use mic input and speaker output.
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N9YNG
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« Reply #7 on: January 05, 2012, 11:22:13 AM »

One reason why the data mode may not be working right:

Did you check the digital gain?  I don't know what menu item it is on the FT-450.  I have a FT-857D, and I had to turn the digital gain WAY, WAY down.  It's default is 50, I had to set it to something like 5.

Of course, you can do this in HRD too, instead of using the Yaesu Sub-menus.

Going back to using PSK in digital mode will eliminate having to change your gain settings when you use voice.
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VA7CPC
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« Reply #8 on: January 05, 2012, 08:22:59 PM »

There's no "digital gain" adjustment on the FT-450.   You have match the input voltage to the rig's sensitivity -- maybe 200 mv on the DATA IN jack, I don't know what it is for the mic input.

        charles
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W8JX
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« Reply #9 on: January 05, 2012, 09:55:29 PM »

There's no "digital gain" adjustment on the FT-450.   You have match the input voltage to the rig's sensitivity -- maybe 200 mv on the DATA IN jack, I don't know what it is for the mic input.

        charles

This is very strange if it does not because my "old" TS-570 and newer TS-480 both have separate levels for audio in and out via data jack on rig.
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N9YNG
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« Reply #10 on: January 08, 2012, 03:39:33 PM »

There's no "digital gain" adjustment on the FT-450.   You have match the input voltage to the rig's sensitivity -- maybe 200 mv on the DATA IN jack, I don't know what it is for the mic input.

        charles

Dang, I was wrong.  That's what I get for assuming.  My bad! Roll Eyes
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VA7CPC
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« Reply #11 on: January 08, 2012, 08:38:05 PM »

. . .

Dang, I was wrong.  That's what I get for assuming.  My bad! Roll Eyes

Don't worry.  There's one on my desk, and I know _all_ the problems.<g>  Yeasu did a lot of things right, and a few things wrong -- no "digital gain" was one of the mistakes.

           Charles
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N9YNG
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« Reply #12 on: January 09, 2012, 04:36:16 AM »

. . .

Dang, I was wrong.  That's what I get for assuming.  My bad! Roll Eyes

Don't worry.  There's one on my desk, and I know _all_ the problems.<g>  Yeasu did a lot of things right, and a few things wrong -- no "digital gain" was one of the mistakes.

           Charles

With the increasing popularity of digital modes, especially with the new ham, I think this is unfortunate.
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