Magnum S9 No TX

[Craigy]

Hi Guys , im struggling with a magnum s9 , it had a catastrophic failure of the finals which took out the regulator and even the tx switching transistor, Now after replacing all the mosfets and biasing them up correctly i have a radio that is transmitting , but at a very low level nothing is getting to the finals ...does anyone have a schematic with voltages?

 

[sonoma]

-if the info you need is not here on cbtricks you will have to contact Magnum for the info.unless some one here has it .

http://www.cbtricks.com/radios/rflimited/magnum_s9/index.htm

 

[Craigy]

Thanks for the reply ...im looking at transmitter alignment on the cb tricks page ...but cannot even find the mythical r102 or test point 6 to begin the process....where is it??

Acccording to the cbtricks layout it should be very obvious as to where it is, on my magnum i see r101 and 103 but the test point has done a wander

 

[sonoma]

all I know is looking at the picture lay out. will this help.I have the magnum 3000b radios which has the same board in at your radio and I found it on that one years ago.

http://www.cbtricks.com/radios/rflimited/magnum_s9/magnum_s9_c1969_adj.htm

 

[sonoma]

after thinking about it I remember one that did not have the test point in place but there was a solder pad you can put a pin in place to get your reading if yours is like that just look at the solder pads. the pin may have been left out.

 

[Craigy]

i have a heathy vco but nothing coming out of the mixer...wierd

we have rx but no rf out of L42

 

[sonoma]

I know L40, L42 and L43 and L44 have to be adjusted right or you will kill the TX. a jackson has the same set up in that area and if you do not set them on each end of the channels it will go hay wire. I had a similar problem on the Jackson radios and it caused a dead key carrier on the SSB channels. had to get them done right.
make sure you check the low channels and the high channels to balance these out.

 

[Craigy]

I have not got as far as adjusting the coils yet as i have zilch coming out , i will desolder the cover on the mixer to test the transistors inside. Should see something on the scope and im not...

 

[Craigy]

had a look under the cover and all the transistors check out ok but output from mixer woefully low and tight,...im seeing 200 mW on band d and nothing elesewhere


L40, L42 and l43 and L44 ..only getting a smidge of output on one perhaps 2 bands while rest is dead unless i specifically tune for that band

i dont understand wh its so tight,,i got the radio after another tech supposedly fixed it with only a few watts out ...very strange

Any idea what is a typical peak to peak output of a working mixer?