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ALC control on Kenwood 530s / 830s




 
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Author Topic: ALC control on Kenwood 530s / 830s  (Read 325 times)
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KA2PTE
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« on: March 31, 2021, 06:18:29 PM »

Tried this method of controling the ALC for purposes of reducing the power to drive
my Viking Thunderbolt linear, where pin 6 is fed a varying DC input via a 9v battery.

Turns out nothing happened at all when I adjusted the control with 9v on it. I was getting for sure
a varying voltage on the wiper and used a 12v supply with a 78L09 vreg chip on it to knock the voltage down.

Im told there are some resistors that age over time and go out of spec in these hybrids. Has anyone heard which ones they are?

Oops, sorry the Hybrids are SSB riggs, forgot !


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« Reply #1 on: April 01, 2021, 12:23:12 AM »

The remote connector connections on the 520/820's are different from the remote connector on the 830s.

On the 830, there's no direct ground connection on any of the pins. You have to add one. Pin 7 is available.
Also note that the front panel Carrier Level Control will vary the RF output only in the CW mode. You'll probably have to use a two tone audio input to the 830, to adjust the RF drive down with the battery pot mod.


* ken830-remote-socket.jpg (35.63 KB, 472x532 - viewed 18 times.)

* ken830-remote-table.jpg (38.5 KB, 782x579 - viewed 14 times.)
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KA2PTE
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« Reply #2 on: April 01, 2021, 11:13:24 PM »

Ok my mistake, I had +6v going in to the pin not -6V. Its working !
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« Reply #3 on: April 01, 2021, 11:39:17 PM »

Ok my mistake, I had +6v going in to the pin not -6V. Its working !

Where did you make the ground connection??
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« Reply #4 on: April 02, 2021, 02:23:35 PM »

On the minus side of the potentiometer not the plus.
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« Reply #5 on: April 02, 2021, 03:14:30 PM »

On the minus side of the potentiometer not the plus.

Where did you make the ground connection on the 830/530??
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« Reply #6 on: April 03, 2021, 11:33:10 AM »

Station ground / chassis ground. The positive of the battery tied to it. The DIN plug seems to have no ground, unless theres a pin tied to the outer shell of the plug being used perhaps.

Did more experimenting and tried a 50K linear taper pot with 2 diodes in series with the 9v supply to bring it down a little.  Did not work well, as the power level was fluxuating all the time while engaged. So I tried a higher value 5 meg pot and kept the voltage as it was with the diodes in there dropping it to about 8v, and its performing very stable like it was with the 200k pot in the diagram. So I guess you can go higher with the potentiometer but not too much lower. I think I read someplace that 56uA is about the average current draw from the 9v battery and the 200k pot.

I'm gauging my tests while throwing 100w cw into a dummy load, then powering up the pin and moving the control to see the power level diminish. During a qso on lsb, I moved it down to 10w and back up to near 100w while doing a count, and was told there
was no noticible changes to my speech audio. That was when I had the 200k pot in place. I am guessing with the 5 meg pot it will be fine, but will do a test later to be certain.

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« Reply #7 on: April 03, 2021, 12:44:19 PM »

The shield is ground on that setup.  Usually the shielt is a chassis ground on those DIN style plugs.

I've been using this method of ALC control on a TS440 for a couple decades now.  I installed an RCA on the back and can feed rack gear to the balanced modulator directly.  With the wide AM filter set on TX and rx I've been told by the engineer of KFMB Dan Diego (now sadly SK) that it was the best Kenwood he'd ever heard.

The Kenwood line is great out of the box, but I like to play with things I guess.

Incidentally I also found the same effect by increasing the ALC to where I could get 150 watts out on ssb, then using a  limiter to keep the peaks down to 100 watts.  The battery trick was a lot easier and worked with mic input.

--Shane
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« Reply #8 on: April 03, 2021, 05:26:00 PM »

My two diagrams (from the TS-830S schematic) above, show what pin connections are on the jack.
And, if you just operate CW with the rig, you don't need the battery/pot mod because you can adjust carrier output level from the front panel.  When I need this mod rather then using a battery pot, etc., I use one of those small HP6000 series DC power supplies that has a floating ground  connection (which is different from a chassis ground connection).
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« Reply #9 on: April 03, 2021, 10:40:17 PM »

It does more than adjust the ALC.  It also stops that horrid ALC cutback on the TX audio in am.

--Shane
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KA2PTE
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« Reply #10 on: April 04, 2021, 11:52:03 AM »

The carrier control on the 530S and 830S appear to offer the same kind of result of lower power. My 530's carrier control seemed to operate more linear than the 830 for sure. I dont know if its because the 530 has an older driver tube in it, but for sure the 830 was no way near as linear in range. It would be at zero then quickly up to 30-40w then flatten out someplace between that and 100w, then all 100w no matter what the rest of the way. This was all with a cw test carrier.

I hear you need to be careful as voice peaks can bring you above the setting , I guess during long transmissions.
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« Reply #11 on: April 04, 2021, 12:09:17 PM »

It does more than adjust the ALC.  It also stops that horrid ALC cutback on the TX audio in am.

--Shane
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This really doesn't apply to the Kenwood hybrids with tube finals. In these rigs, the mod is just used to control RF output on SSB.
In the several Icom solid state rigs I had or currently have, the modulation technique they use works fine for me especially when driving a linear. I don't use the mode currently in any of my solid state rigs.
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« Reply #12 on: April 04, 2021, 12:14:17 PM »

The carrier control on the 530S and 830S appear to offer the same kind of result of lower power. My 530's carrier control seemed to operate more linear than the 830 for sure. I dont know if its because the 530 has an older driver tube in it, but for sure the 830 was no way near as linear in range. It would be at zero then quickly up to 30-40w then flatten out someplace between that and 100w, then all 100w no matter what the rest of the way. This was all with a cw test carrier.

I hear you need to be careful as voice peaks can bring you above the setting , I guess during long transmissions.

A two tone signal into the mike input is a good way adjust the mod. A scope on the output of the linear can help in making sure your audio peaks aren't over driving the linear.
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