Stalker IX DX AMC/ALC not working

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13EL121
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Stalker IX DX AMC/ALC not working

Post by 13EL121 » 08 Nov 2019, 06:19

Hi friends,
Got a poor Stalker IX DX which I bring back to working condition. Had to replace all electrolytics etc...
But AMC and ALC are at full blast and can not be regulated. Checked all transistors for ALC and AMC but they are OK. Any ideas would be appreciated.
Thanks, Ralf

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Re: Stalker IX DX AMC/ALC not working

Post by 13EL121 » 08 Nov 2019, 06:22

Sry double post due sql error. Please delete.

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Re: Stalker IX DX AMC/ALC not working

Post by cb4ever104 » 09 Nov 2019, 11:03

There's a lot of ways to do this Ralf , so you'll need to go through the diagram . I've seen people do some strange things to radios to max these out . The best one was someone put one of the transistors in backwards to disable the circuit :shock:
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Re: Stalker IX DX AMC/ALC not working

Post by ch25 » 09 Nov 2019, 11:22

Measure resistance between collector TR48 and emitter of TR33.
You can't have too many antennas...

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Re: Stalker IX DX AMC/ALC not working

Post by 13EL121 » 09 Nov 2019, 11:25

Right friends, will have a closer look and measure some voltages. Have a working Stalker9 here.
This was a poor radio. After some love, rewiring the NB ANL and PA switch and new caps ist working again, but AGC and AMC pots do nothing.
Thanks for the tip of resistance between Transistors. Will check tomorrow. 👍

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Re: Stalker IX DX AMC/ALC not working

Post by astradyne » 10 Nov 2019, 09:33

Have you checked the A1012 for voltage out? When these go open circuit they usually cause the issue you mention.
Never, ever, ever....bloody anything ever!

Far too many radio's to list here. But I do own a legal one...

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Re: Stalker IX DX AMC/ALC not working

Post by 13EL121 » 10 Nov 2019, 10:49

Yes, preowner swapped the 1012 to a BD244 or something, but voltage switching and output regulation via VR in AM FM works.

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Re: Stalker IX DX AMC/ALC not working

Post by 13EL121 » 11 Nov 2019, 21:11

ch25 wrote:
09 Nov 2019, 11:22
Measure resistance between collector TR48 and emitter of TR33.
Restance between both is 3,3k Ohm. Swapped TR48 back to a 2sa1012. Now more SSB power, but AMC and ALC still at full blast.

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Re: Stalker IX DX AMC/ALC not working

Post by ch25 » 11 Nov 2019, 21:38

stalker_ix_dx_sch-unlocked.jpg
There must be something wrong in that area.
Chris
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You can't have too many antennas...

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Re: Stalker IX DX AMC/ALC not working

Post by 13EL121 » 11 Nov 2019, 22:22

I hope so Chris. 🥴
Strange thing. TR31 measures ok too. Next step are the Diodes. But in circuit they seem to be OK.

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Re: Stalker IX DX AMC/ALC not working

Post by 13EL121 » 12 Nov 2019, 20:12

Many thanks guys for the input. Just found the fault. There was a solder bridge near mic Socket. That shorted TR31 i think. I removed the solder bridge and resolderd both points. AMC and ALC now working fine again. 👍
Radio is now back on air and working excellent.
IMG_20191112_210123.jpg
IMG_20191112_210237.jpg
73s Ralf
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Re: Stalker IX DX AMC/ALC not working

Post by cb4ever104 » 13 Nov 2019, 11:24

Good stuff Ralf . I usually learn how individual circuits work when I get those kinds of faults .
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Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.

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Re: Stalker IX DX AMC/ALC not working

Post by 13EL121 » 13 Nov 2019, 12:01

Thanks Paul, it was hardly to see. I cleaned the PCB with isopropyl alcohol, so I could better see the solder joints. It was very nasty, but now it works fine.

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