No subject

amp, or in the house....
there is a 99 percent probability that you have one or more of the 
filter caps going or gone.
Now, an ohmmeter check of a cap will show if it is dead shorted ... but 
it is also possible ...
again personal experience .... that the cap could show good on the 
meter, yet be leaky enough
that when it is hit with the high voltage, it will temporarily short to 
ground, popping breakers.

It took me about an hour or so to find this problem with an sb 200 that 
I owned.   I had one
cap dead short ... yet when I replaced it, I was still popping the amp 
circuit breakers  yet the
ohm test of another cap that was bad didnt reveal a short....     



Karl France wrote:

> 
>I contacted a buddy of mine who is an electronic design engineer (retired)  
>and this is his recommendations ....hope this helps
> 
>Karl
>W5QJE
> 
> 
>OK, trouble shooting recommendations:
> 
>1.  Pull the tubes out------ power up and see what happens.
>     Sounds like a High Voltage problem there.  If  the 2400
>      VDC is there, no malfunctions, then the HV  power 
>      supply is OK probably.  
> 
>2.   Check to see that you have the Neg 120 vdc on the 
>      tube grid connection of the tubes.   When not keyed, 
>      it should have the neg 120 vdc there.  
> 
>3.   Check the 6.3vdc filliment voltage AC VOLTAGE.  If it  is
>      there, then it is probable that your  ceramic capacitors 
>      are OK.  30+ year old TV type ceramic  caps look bad
>       anyway, but are usually  OK.   
> 
>4.    Plug in ONE tube at a time.  One tube in,  one out. Try 
>       operating the linear amplifier 250  watts output max.  If
>       OK, then put in the second tube and  try again.
>MAKE SURE-----YOU DO NOT OVER DRIVE THE AMPLIFIER.  IF YOU GO OVER 550  WATTS 
>OUTPUT, THEN YOU CAN REACH THE LIMITS OF THE TWO 8 AMP CIRCUIT  
>BREAKERS--------ESPECIALLY KEY DOWN SITUATIONS.  
> 
>These amplifiers will put out 700 watts, but not for long.  Keep the  output 
>power down to 550 watts or less.  Detune using the LOAD variable  capacitor on 
>the linear amplifier, this will reduce RF drive from the  transceiver.  OR 
>reduce transceiver RF drive to control the output  power.  ALWAYS tune up with 
>about 50 watts drive, before you run the power  up to full output.  
> 
>THOSE 8 amp circuit breakers are there to protect the high voltage power  
>supply and TUBES.   When you push the amplifer OVER 500 watts output,  then you 
>are overloading the HV power supply.  HEATHKIT specified the  amplifier at 1000 
>WATTS (1 KW) INPUT POWER, because that is the  way the FCC specified the 
>power limit back in the 1960's when this amplifier was  approved.  It does take 
>about 120 watts to drive the amplifier to full  output on 10 meters only. 
>Watch the on-board SWR/PWR meter-----limit power output to 500 watts and  you 
>should be OK
> 
>                                CARL K8IHQ
>
>
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