On Wed, 12 Sep 2007 13:46:32 -0700, wrote:

On Sep 11, 8:06 pm, "Philo" wrote:


I sincerely think you would have a lot more fun trying to clone a HW8.

There is no need to pursue much linearity in a cw transmitter ... unless you
try to build an almost unpractical one.

Granted, Philo...

Here's how the argument goes:
- goal: minimal part count + ability to put clean QRP signal anywhere
- DC drain no problem - class C not indispensable
- linear broadband keeps part count down and adds little spurs
- do all filtering after PA, if possible with multi-tuned tanks or
plug-in LPFs

However, my request is now moot.... I don know what possessed me when
I did my previous searches, but the aforesaid info CAN be found on the
web.

Here is one example:

http://www.qsl.net/ik4auy/article_4_english.htm

Plenty of usable ideas.

I am now experimenting with a simple 2-stage drive (2nd stage push-
pull) with plenty of negative feedback. May be enough to go on air.



You might want to check out the Mistubishi RD16HHF1 RF MOSFET. They
are available from RF Parts at $4.20 apiece, and have similar specs to
the 2SC1969, except with 4 dB more gain. The data sheet tests them at
12.5VDC @ 30 MHz. W7ZOI did a post to the EMRFD Yahoo group about
them. I bought 35 for our QRP club at $3.10 each from RF Parts.

By the way, CB shops advertise them as "drop-in replacements" for the
2SC1969. Grain of salt there........