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Author Topic: TS-590 Power Spike Resolution  (Read 7916 times)
W7ARX
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Posts: 430




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« on: July 29, 2013, 11:41:10 AM »

Someone mentioned I ought to make this a separate thread so here goes.  I have read that the 590 (like many, many other radios) spikes (overshoots) the power to the amplifier causing in some cases, to pop a fault with the amp (as a minimum).  I have read that version 1.07 software supposedly "fixes" this and yet someone else states, it doesn't and that a hardware fix is required, which, when I ask Kenwood, they state "what hardware fix".  SO, is there a fix for this issue over overshoot with the 590 or not?
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KE4JOY
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« Reply #1 on: July 29, 2013, 12:21:18 PM »

Maybe not drive at full output?
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W7ARX
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Posts: 430




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« Reply #2 on: July 29, 2013, 12:31:49 PM »

When you drive an amplifier, you typically use from 30-50 watts to drive the amp to full output.  At reduced input, you would see reduced amp output.  Problem is, when you hit the amp with say 30 watts that would normally give you 400 watts out, it may spike as high as 1200 watts and drop to the 400 watt mark once you stay keyed.  Not a good thing for an amp.

There is supposedly either a software fix or combined software/hardware fix for this at Kenwood.  I can't get them to tell me (else talking to the wrong tech there) which is correct or if even there is an actualy fix.  Many radios out there do this and it isn't healthy for the amp not to mention the amount of splatter one would cause with this issue (which I hear on the bands a lot).
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M6GOM
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« Reply #3 on: July 29, 2013, 03:35:43 PM »

The "fix" is to reduce the ALC reference voltage so that the ALC is active or to use an external ALC reference.

To call it a "Kenwood TS590" issue is a bit of a misnomer. Many radios suffer the same problem to some extent. Even the Yaesu FT1000 does so its been an issue for a while. Its only now really a problem because more people run solid state amps or amps with "smart" front ends that detect the over-drive.

If you don't run an amp or run an old one you'll not notice a problem in normal use without test equipment.
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WX7G
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« Reply #4 on: July 29, 2013, 04:11:19 PM »

Another fix is to place a 3 dB power attenuator between the radio and the amp. MFJ should make such a thing.
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K8AXW
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Posts: 3837




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« Reply #5 on: July 29, 2013, 05:06:35 PM »

QST recently (like within the past year) on how to build a 2db attenuator that takes care of this overshoot problem.  With the relatively new Caddock resistors, this is a very easy thing to do.  Works fine for me.
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W7ARX
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Posts: 430




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« Reply #6 on: July 29, 2013, 05:13:20 PM »

Don't think I saw that article and don't believe I ever saw any MFJ product like that...any reference to the MFJ Model, could look it up and make something like that..
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AD5X
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« Reply #7 on: July 29, 2013, 06:01:53 PM »

I wrote that article, and it is also on my website (www.ad5x.com).  It works great in that you don't have to re-adjust your transmitter power when you turn on your amp.  And if the transceiver only overshoots to full transmit power, it solves that problem as well.  But some transceivers overshoot well above full transmit power, and it won't help that.  As an example, my IC-706MKII overshoots to 140 watts regardless of power setting.  I understand that some other transceivers are even worse.  What does the TS-590 do?

Phil - AD5X
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W7ARX
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« Reply #8 on: July 29, 2013, 06:18:43 PM »

WHen I get a chance, will check it and let you know.  I haven't had a moment to get into it much this week.
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W8JX
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Posts: 5789




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« Reply #9 on: July 29, 2013, 07:45:22 PM »

The "fix" is to reduce the ALC reference voltage so that the ALC is active or to use an external ALC reference.

To call it a "Kenwood TS590" issue is a bit of a misnomer. Many radios suffer the same problem to some extent. Even the Yaesu FT1000 does so its been an issue for a while. Its only now really a problem because more people run solid state amps or amps with "smart" front ends that detect the over-drive.

If you don't run an amp or run an old one you'll not notice a problem in normal use without test equipment.

Then problem is some set drive at max power and depend on ALC to throttle it. The fix it to forget ALC and manually reduce drive. I run rig output power at 50 watts barefoot and 50 watts with a amp in line.
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NO2A
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Posts: 784




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« Reply #10 on: July 29, 2013, 09:44:47 PM »

How much power does the TS-590S peak at when it spikes? My FT-857D spikes up to 100 watts,but my AL-80A can handle that.
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G3RZP
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Posts: 4589




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« Reply #11 on: July 30, 2013, 01:29:33 AM »

I'm not up on the innards of modern rigs, but don't nearly all of them rely on ALC for power control? If there isn't a separate way of controlling drive, you get stuck with it. Some older rigs had an advantage there...

ALC has always seemed to me to be a bit of shutting the stable door after the horse has bolted....
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M6GOM
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Posts: 907




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« Reply #12 on: July 30, 2013, 05:20:36 AM »

What does the TS-590 do?

Phil - AD5X

Basically doubles what the power is set to so 100W becomes 200W, 50W becomes 100W, 25W becomes 50W etc.
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K8AXW
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Posts: 3837




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« Reply #13 on: July 30, 2013, 09:23:45 AM »

Phil:  Thanks for jumping in here.  Your circuit is one that should be bookmarked by any ham that runs a linear.

Al - K8AXW
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W7ARX
Member

Posts: 430




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« Reply #14 on: July 30, 2013, 09:53:33 AM »

I wrote that article, and it is also on my website (www.ad5x.com).  It works great in that you don't have to re-adjust your transmitter power when you turn on your amp.  And if the transceiver only overshoots to full transmit power, it solves that problem as well.  But some transceivers overshoot well above full transmit power, and it won't help that.  As an example, my IC-706MKII overshoots to 140 watts regardless of power setting.  I understand that some other transceivers are even worse.  What does the TS-590 do?

Phil - AD5X

Phil
Which article on your web page..looking but haven't seen it...I must be blind...
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