[4W FM Transmitter]

Replaced T2 with another transistor Blw29
T2 gets hot but does not need a heatsink
getting 1- 1 1/2 watts out of it

I find this difficult to tune.
could the tuning capacitor be replaced with one of a smaller value
perhaps in parallel with another capicitor
I want to run this at 88Mhz. What values should I use?

[4W FM Transmitter]

More like the one on the right
components mounted on non metalic side
of board
Longish component leads esp T1 ?
Only difference compnents fairly close

[4W FM Transmitter]

This problem seems to be with the oscillator
power measured at point between osc and amp
T1 has no heatsink!
Can anything else cause this problem?

can tune roughly

[4W FM Transmitter]

Made a heatsink out of a section of thick (3mm) copper tubing lower section fits over T2  6 vertical cuts made from top  20 mm long,    pieces bent 90 degrees to tubing.
small fan from cpu wired to top of heatsink

Using rundown 9v battery for power while tuning
Difficult,  trimmers small even with plastic tuning tool
presence of hand affects tuning.

oscillator var cap replaced  with one from FM radio
Using probe made from 2 diodes 2 capacitors to measure output

Output power drops dramatically at higher frquencies
soldering rather messy,  component placement could be better,
Is this a possible cause of this problem?





             

[4W FM Transmitter]

How large should the heatsink be?

[4W FM Transmitter]

I build this circuit However T2 always seems to burn out
after a few seconds even with heatsink! Is there a nother transister that would be good as replacement?