TS 830S with very low output - UK Vintage Radio Repair and Restoration Discussion Forum

nemo1956 · 12th Dec 2016, 8:42 am

I have one of these a long time ago and loved it.
Now I have a different one that I bought from E-bay some 12 months ago but it had a fault on it. No output.
I found that problem and sort it out but the output was only 80 watts.
I change both the PA valves and the driver valve but now when I switch it on I only get 5 watts when cold and after 20 minuets of running the heaters I get 20 watts. so I left it to run for another hour then I get 80 watts again.
I replace the driver valve with the old one with no difference.

I cant seem to locate this fault at all. I wont to get it fully working by the end of the winter so I can again enjoy my 830 with a pint of beer in the summer and all those rag those.

Paul. G0MIH/HS0ZLQ

G3PIJpeter · 12th Dec 2016, 11:18 pm

Paul -

I suggest you download the operator's (instruction) manual and the service manual from the webpage at http://www.wb4hfn.com/KENWOOD/Kenwood-Manuals.htm

You should check the voltages on the 6146 cathode, screen and control grids on both receive and transmit. These voltages are listed on the circuit diagram in the service manual. I suspect there is something wrong with the resistors in the screen grid supply or in the cathode circuit. Bear in mind that there is 850 volts on the anodes and that bodily contact with this is likely to kill you - take the usual sensible precautions.

Finally, there is an excellent Kenwood 'Hybrids' group at https://groups.yahoo.com/neo/groups/...0_530_830/info - I found a huge source of experience and advice here that helped to get my TS830S going a few weeks ago.

Best wishes - Peter G3PIJ

G3PIJpeter · 12th Dec 2016, 11:43 pm

I have copied the PA circuit and voltages from the high-res circuit diagram. Not sure how well the voltages will show up on this thumbnail. Suggest you also search for the high-res diagram - available separately from the manuals.
- Peter G3PIJ

Radio Wrangler · 12th Dec 2016, 11:50 pm

Check DC first, but there are also things which don't show up on DC voltages that can reduce output power like bad screen decouplers and bad screen resistors.... also the decoupler at the end of the HT feed choke.

You have checked that ALC isn't operating when it shouldn't?

David

12th Dec 2016, 8:42 am	#1
nemo1956 Triode Join Date: May 2016 Location: Phimai, Thailand. Posts: 49	TS 830S with very low output I have one of these a long time ago and loved it. Now I have a different one that I bought from E-bay some 12 months ago but it had a fault on it. No output. I found that problem and sort it out but the output was only 80 watts. I change both the PA valves and the driver valve but now when I switch it on I only get 5 watts when cold and after 20 minuets of running the heaters I get 20 watts. so I left it to run for another hour then I get 80 watts again. I replace the driver valve with the old one with no difference. I cant seem to locate this fault at all. I wont to get it fully working by the end of the winter so I can again enjoy my 830 with a pint of beer in the summer and all those rag those. Paul. G0MIH/HS0ZLQ

12th Dec 2016, 11:18 pm	#2
G3PIJpeter Hexode Join Date: Nov 2011 Location: Chippenham, Wiltshire, UK. Posts: 323	Re: TS 830S with very low output Paul - I suggest you download the operator's (instruction) manual and the service manual from the webpage at http://www.wb4hfn.com/KENWOOD/Kenwood-Manuals.htm You should check the voltages on the 6146 cathode, screen and control grids on both receive and transmit. These voltages are listed on the circuit diagram in the service manual. I suspect there is something wrong with the resistors in the screen grid supply or in the cathode circuit. Bear in mind that there is 850 volts on the anodes and that bodily contact with this is likely to kill you - take the usual sensible precautions. Finally, there is an excellent Kenwood 'Hybrids' group at https://groups.yahoo.com/neo/groups/...0_530_830/info - I found a huge source of experience and advice here that helped to get my TS830S going a few weeks ago. Best wishes - Peter G3PIJ

12th Dec 2016, 11:50 pm	#4
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,901	Re: TS 830S with very low output Check DC first, but there are also things which don't show up on DC voltages that can reduce output power like bad screen decouplers and bad screen resistors.... also the decoupler at the end of the HT feed choke. You have checked that ALC isn't operating when it shouldn't? David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done