[Amps] Real danger to use the ORANGE button

[Roger (K8RI)]

Jim, how far off the frequency were you listening?  I may need to do 
some expirmenting,

120 watts is plenty. A clean signal at 120W is a bonus.

The shop has been a disaster area, but the rerod tower base is now out 
of the shop and in the ground giving more room. A food scrubbing of the 
floor and that area is going to get a couple coats of 2 part epoxy.

If my back holds out, I plan on working on that area tomorrow..

73

Roger (K8RI)


There is virtually NO air going past heat sinks 1+2..... only 3+4. ## I 
have used class A for brief test purposes..into a dummy load...while 
listening off freq..with a 2nd MK-V. When toggling the MK-V between 
Class A..and Class AB.... both running the same 75 watts pep out....the 
difference between the two modes is astounding. The imd crap way off 
freq, drops from real loud to zero, its that big a difference. However 
the cooling on the MK-V negates using it in Class A on ssb. However the 
bias can be tweaked for each transistor individually, for both the pair 
of driver transistors and also the pair of high power final transistors. 
So FOUR bias adjustments to tweak for class A....and FOUR more bias 
adjustments for class AB..... 8 x bias adjustments in all......and all 8 
pots are INTERNAL. ## the best you can do with the MK-V is to either 
lower the idle currents a whole bunch when in Class A mode.... OR 
increase the idle currents when in Class AB mode. In normal class AB 
mode, EACH high power transistor sucks 1A.....2 A for the pair.. In 
normal Class A mode, EACH high power transistor sucks 5A...10A in total. 
In normal class AB operation, the MK-V....when run at 60-120 watts pep 
output..is very clean vs running it at 200w pep out.


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