MOTM

There are a number of small radio receiver designs that use varactor 
diode tuning.  A varactor is a diode that act like a narrow-range 
variable cap when a bias voltage is applied.  This allows the 
designer to use a potentiomer for tuning.  Naturally, ANY voltage 
source could be used.

Check out the ARRL Radio Amateur's Handbook for QRP (low power)
tranceiver designs.  Another excellent resource would be Wes Hayward 
and the late Doug DeMaw's Solid State Design for the Radio Amateur.  
This book is heavy on practical receiver design, pcb layout and all 
facets of radio frequency construction.

The British equivalent to the ARRL also has some wonderful 
publications.  For kits, check out MFJ Manufacturing (I don't know 
their url) and Ten Tec.  These are US companies that produce 
reasonably priced gear in kit form and pre-assembled.  MFJ gets a bad 
rap on quality (known to hams as Mighty Fine Junk) which is 
undeserved.  I can personally vouch for the excellence of Ten Tec - 
their Omni 6+ is my main tranceiver and many beleive it to be the 
best ever produced.

Lastly, I have built a variation of Ken Stone's Tube VCA.  When radio 
frequency control voltages are used, it produces a WILD spectra of 
sound.  If you like it strange, RF is king!  Be careful, however, as 
RF can damage some of the audio components in your system.  I am not 
responsible for any damage or personal injury as a result of your 
doing the stupid things I do...

Chub - KG9MS .-. .-. -.-

--- In motm@yahoogroups.com, "Sikorsky" <vulture.squadron@s...> wrote:
> > Has anyone tried to build a voltage controlled short wave radio
> > module?
> 
> i've been toying with the idea for a while - the last radio i 
bought for
> experimentation got liberated by my girlfriend and now lives out a 
peaceful
> existence permanently tuned to radio 4
> i've thought about building a couple of crystal radios to use as 
voltage
> sources, but as always, never quite gotten around to it. to voltage 
control
> the tuning of the radio you'd need to control the variable tuning 
capacitor
> (or don't radios have those anymore...)
> 
> i did get a couple of really cheap walkman type fm radios as 
corporate
> gifts, but again - one of them got liberated - they only run on 2 x 
AAA
> batteries, so i could power them from say the UEG, clamping the 
voltage at
> 0-3v (or not as the case may be !)
> 
> i feel a bank holiday afternoon of discover here (i just dug out 
the last fm
> radio)
> nurse - the pliers !
> 
> cheers
> paul b
> sheffield
> uk