BATC Forum

Hi all,

In order to get a bit more power out of the modulator board, I intend to replace the 10.5 dB attenuator in front of the final transistor (R51,R52,R53) by a 6 dB attenuator(150,39,150 ohms resistors).
Any problem doing this? Looking at the datasheet of the transistor, this looks ok, but I prefer to ask the question!

Best 73,
Roland F8CHK

Confirm that with 180,30,180 this correspond to 5dB, we have 32 mW out with no issues and sufficient to enter a relay at 15km with HB9CV on 437Mhz..

That change may look good on paper but you should check with a spectrum analyzer to see that you haven't caused sideband growth.

The MMG3H21NT1 was the final choice for the output driver because it is cheaper and more widely available than the SKY65017-70LF.
The SKY65017-70LF has a flatter gain curve to give you a few more dB at 23cm. Digi-Key has 16,327 in stock 863-1063-1-ND.