Batboard

is it at all possible to ? move a 400 - 420 amp up to 450 - 480 band? ive been told by a few friends that it may only have diferent coil lengths and some different values of the caps surrounding the main final? has anyone ever done this and sucseeded ? if so id love to hear about it !. thanks for your time and have a great day/night

Motoguy

Whats the amp from, most of Motorola's amp designs are around micro-strips on ceramic substrates, not easy to change.

ok , after speaking to a few other people about this amp, some say it may be posible to change the lengths of the microstrips . since its low uhf they are longer than needed, so with some trial and error we may be able to shorten these lengths in the radio and acheive a higher band ? what are your thoughts? cheers

Not only do you have to redesign the microstrip elements on the input and output of the transistor, you also have to define the operating bandwidth of the device itself.

If the transistor is designed for a wide bandwidth of say, 430-480, then you can modify the amp for use in your intended band.

The matching components, and all passive devices must either be changed, or at the very least, retuned to you maintain a proper input and output impedance, or the device will probably suffer from oscillations and be driven into thermal overload and burn out, thanks to those oscillations.

If drive is removed but power is still applied, the self-excitation of the oscillations can keep the transistor in a continual power output cycle and continue to operate while burning itself out with no external drive being applied.