The book Crystal Sets to Sideband has discouraged frequencies above the low VHF band due to all of the problems with wires acting as inductors and difficulty on a stable Variable frequency Oscillator.

My goal is to build a 421 MHz 10 watt CW signal.

Would it be possible to build this out of discrete components like transistors, inductors, etc.?

Or is the frequency too high that it just isn't practical without microchips with tiny little traces to keep the lead inductance down?

  • \$\begingroup\$ Have you considered creating a Colpitts oscillator? \$\endgroup\$
    – Shabab
    Oct 28, 2013 at 17:28
  • 1
    \$\begingroup\$ You can definitely go discrete but it would be best to do this on a PCB. \$\endgroup\$
    – scld
    Oct 28, 2013 at 18:20
  • \$\begingroup\$ standard transistors with good building practices will work on this frequencies no problem. \$\endgroup\$
    – jun magno
    Jul 3, 2014 at 22:23

1 Answer 1


No problem at this frequency for standard surface mount components and colpitts is the likely oscillator to choose. However, getting it tuned to the frequency you require will be impossible without either a very good scope, an average spectrum analyser or some form of frequency measuring device.

Next problem is taking the 2 or 3 volt p-p signal and amplifying it to produce 10 watts into 50 ohms. Not easy to do without a fairly decent spectrum analyser and some decent filter design.

Presumably you'll want to modulate the carrier so this means probably adding a varactor to the colpitts. This does FM.


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