[Kenwood] Kenwood TS-830S no tune on 160m

[Steve H]

Worked on this some more. Did the neutralization procedure as per K4EAA's 
site faq. Was able to cancel out 60mV
pp excess RF, however problem is still there.

Have tried another set of known good tubes that work n a 530S Kenwood ok, so 
its not the tubes. Also swapped RF driver tubes
so its not that.

I was told to check the negative bias on the finals, which I probably will 
do later today.

Went back into the final cage and unhooked the caps I put in and put them on 
the tester. 1 reads sort of low, but its in spec
at the 20% tolderance the manufacturer specifies. I did save all the old 
original caps, so I may try putting them in one at a time
in case I got a bad new cap, which is a possibility these days.

It seems like the plate current is ok when you first transmit a carrier, the 
current is momentarily in the range it ought to be, then
it jumps to almost 200mA, and will increase, sort of like somethings 
breaking down with the voltage applied. I guess I cant rule out a
dirty contact on the band switch, but I have cleaned it several times with 
contact cleaner. The spots near the back in the final cage are harder to
treat tho.



KA2PTE


----- Original Message ----- 
From: "Steve H" <teknoskillz at comcast.net>
To: <kenwood at mailman.qth.net>
Sent: Sunday, June 14, 2020 10:39 PM
Subject: [Kenwood] Kenwood TS-830S no tune on 160m


> Did alot of work on this one and almost all ok except on 160m when you try 
> to tune up in CW , the plate dip is hard to narrow down, as it seems to 
> creep up to about 270mA gradually and the 6146 tubes glow orange brightly 
> on the plates which is not good.
>
> It does this into a dummy load too as well as the antenna. Tried another 
> set of known good tubes, and had to set the idle current back to 50Ma as 
> it went down to 10mA with the swap, but same thing.
>
> I can modulate in USB and LSB ok, and Im putting out some power enough to 
> make contacts not too far away. Someone said theres some oscillation 
> taking place somewhere.
>
> I read tube neutralization or lack thereof can cause this oscillaiton, but 
> its only on 160m which is odd. Anyone ever hear of this before?
>
> Steve
> KA2PTE
>
>
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