Help restroing my new Heathkit

[Bob Burns]

Hi Eric
 
1. The difference between a 25K and 50K mic is probably not worth worrying  
about.
 
2. According to the circuit diagram there should be between 1.2 and 2.9V RF 
 at the input of the PA module on transmit depending on the band in use. I 
would  connect your mic and see if that RF is present on Tx with a whistle. 
If it is  then you have a PA fault. If not then you need to do some basic 
fault finding  further back in the Tx.
 
3. The three pairs of PA devices are all bipolar so you should be able to  
get an indication if any of them have popped by checking the device 
junctions  with an ohm meter with the rig switched off. You may need to disconnect 
the  supply feed for this test and bear in mind the surrounding components 
which will  affect the resistance readings. Look on the PA board to see if 
anything has been  fried and check if any of the resistors are open circuit. Be 
careful removing  any of the PA devices as they may contain beryllium 
oxide, the dust of which is  extremely hazardous to your health.
 
4. You could also check the supply current into the PA board on Tx which  
should show the total collector current due to the forward bias of the three  
stages if nothing else. It should also increase on Tx with a whistle if RF 
is  getting to the PA board.
 
5. Do you have a user manual or circuit diagram?
 
73

Bob 

G3OOU
G-QRP  6907
Joint site with Crystal Palace Radio & Electronics Club: _www.g3oou.co.uk_ 
(http://www.g3oou.co.uk/) 
My technical site: _http://www.qsl.net/g3oou/_ (http://www.qsl.net/g3oou/) 

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