On Wed, Mar 13, 2024 at 11:23?PM Greg McCain via <gamccain50=[email protected]> wrote:
Hi gang,? Not complaining ...? ?Just curious.
I had recently built 3 of the 50W amps ( 15M, 20M and 40M). Want to use them for a little extra punch (say 10 to no more than 20 watts out) for field semi-portable 'digi' work (FT8, J8Call, WSPR) . . .? well, just because.??I built all three as '12 volt' versions.?
?I set the drive bias exactly as described in the instructions. The builds went well and the amps appear to output as described in the manual(s)./graphs.
I was just wondering why the 40 meter version is 'hotter' than say the 20 meter version which is hotter than the 15 meter version.
I found that I can get 10 Watts OUT with the following Watts IN from my K2.
15M - approx 4.5 Watts IN 20M - approx 2 Watts IN 40M -? LOTS of WATTS OUT (Too Many) with Just 1 Watt in !!
** For the 40M, I found if I backed down the bias, I could get 10 Watts out by setting the K2 for between 0.1 and 0.2 Watts out. Yep 'tenths' of a Watt.?
Is my stumbling on the bias backdown a potential problem point?
Or, perhaps I should make up some PI attenuator circuits to add to the Transmit circuit chains in the AMPs where needed to tone down the 3.6 - 3.9 Watts that my new QMX is producing??
