Kenwood TS-450 Final Bias adjust

[Heliman]

I'm replacing the finals (2SC2879) in my Kenwood TS-450. The service manual described how to set the idle current using VR1 and VR2. My question is, where in the circuit is the ammeter connected. Ive been told by some to connect in series with the 12v line in but the manual says ANT on rear panel.

 

[davenn]

Ive been told by some to connect in series with the 12v line in but the manual says ANT on rear panel.

what page/section in the manual did you read that ?

 

[Heliman]

what page/section in the manual did you read that ?

Its in the service manual. I included a snapshot of the page.

 

[Heliman]

Its in the service manual. I included a snapshot of the page.

I'm sure the manual is in error. The snapshot I provided shows the final bias setting. The column shows measurement taking at rear panel on ANT terminal

 

[davenn]

I'm sure the manual is in error. The snapshot I provided shows the final bias setting. The column shows measurement taking at rear panel on ANT terminal

that's why I asked you to clarify, and I did find the manual

it doesn't say in your above clip anything about measurement at the antenna .... really not sure where you are getting that from ??

 

[Heliman]

that's why I asked you to clarify, and I did find the manual

it says in your above clip anything about tagging measurement at the antenna .... really not sure where you are getting that from ??

 

[davenn]

ahhhh

hmmmm OK I see how that was read .... wonder of the horizontal dividing line was supposed to continue across
between 4 and 5 ?

I am not at home so don't have the manual handy, but I doubt that you will get a DC bias reading at the antenna
because of series capacitors in the output filter stages

 

[Heliman]

I know, that's is what is confusing. Im sure its a misprint or even a error in translating the manual from Japanese.

 

[davenn]

just downloading the manual again

have you read anywhere in the manual the actual text for the measurement procedure,
surely there is something more than just a test table layout ?

 

[Heliman]

There's two 12 volt lines coming from the 12 volt in jack. 1 goes to the collector of the finals and the other goes to the on/off switch. I'm just going to put the ammeter in the line going to the finals.

 

[Heliman]

just downloading the manual again

have you read anywhere in the manual the actual text for the measurement procedure,
surely there is something more than just a test table layout ?

Havnt seen anything in the manual other than that image I uploaded

 

[Heliman]

This service manual is the poorest service manual Ive ever seen

 

[Heliman]

I looked at the service manual to my Kenwood TS-2000 and its really clear as what to do

 

[elebish]

Just hook an ammeter in series with your 50 ohm dummy load at the antenna terminals. I believe 250 Ma is the reading at idle according to you jpg sheet.

 

[davenn]

Just hook an ammeter in series with your 50 ohm dummy load at the antenna terminals. I believe 250 Ma is the reading at idle according to you jpg sheet.

That doesn't sound correct .... idle current is normally done in the collector supply line

 

[Heliman]

I ended up hooking the ammeter in line with the power in line. Turned both VR1 and VR2 all the way down. Checked idle current then added 250ma to each final. Turned out great. Puts out 100 watt and sounds great.