The key is the low power end can be closer together than the high power end.
As a result the power amp takes up about 1/3 the total space, driver maybe 1/4.
There is a shield 2" high copper clad soldered to the ground plane between?
high power and driver and a second one for the driver to low level.? Holes?
in the shield? for power and signal pass through.
The mixers and low level stuff is on another board entirely.? Strictly
power chain from the first amp to final.? ?Band pass is of board with TR.
Coax from mixer filter on low level board to the amp and coax to the
band pass filters both end grounded and all boards placed on a
larger piece of copper clad and grounded to it at many points.
Since Board pieces are cheap a wall around or between things is a
good thing, add shielding and keeps the board stiff.? And unless I'm
trying to be unusually compact ( like a 1W VXO tuned SSB TRX
for 6M in a 4x2x2" box) I let things spread out as there is less
incidental coupling or need for shielding
All leads short and anything that goes to ground does so directly.? I even use SMT
Parts like .1uf caps get soldered to ground and then power or other leads to be
bypassed go to it.? Layout is everything.??
There is not enough difference in Q at lower HF between -6 or -2 material.
FYI the loaded Q of the filters are likely less than 10.
As a result stability has not been an issue even with idling drain current in the
200-250ma area.
Some of the tricks I use.
Allison
