I'm pondering building a 10 MHz CW xmtr. Single band would suit me,
10-50 watts maybe?. I wanna use tubes.
Am thinking about a 2-3 Mhz VFO mixing with an old surplus 7-8 Mc xtal.
I guess a guy could finagle a 2-bander (40/30) with ~8.5 xtal and ~1.5
VFO...hmmm, thats another thought.

Has anyone done something along these lines or maybe a 40/20 rig that I
could scale for 30 meters?

73,
Bill WX4A

Exray wrote:

Am thinking about a 2-3 Mhz VFO mixing with an old surplus 7-8 Mc xtal.

The 10MHz band is so narrow (10.1 through what, 10.14 MHz?) that a
couple of crystals and some rubbering can cover it.

The VFO+mixer scheme is great for a multi-band SSB xcvr but the
complexity really isn't needed in a CW transmitter. Just build a VFO
straight for 10MHz, or double up from 5MHz (lots of 5MHz VFO plans in
all the handbooks) or triple up from 3.3x MHz.

Tim KA0BTD

Tim Shoppa wrote:

Exray wrote:


Am thinking about a 2-3 Mhz VFO mixing with an old surplus 7-8 Mc xtal.


The 10MHz band is so narrow (10.1 through what, 10.14 MHz?) that a
couple of crystals and some rubbering can cover it.

How easy is it to rubber a crystal in a tube oscillator?

(note to OP: If you use any of the older designs for a crystal
oscillator make sure your crystal can handle it -- the older crystals
were physically larger & could handle more power)

The VFO+mixer scheme is great for a multi-band SSB xcvr but the
complexity really isn't needed in a CW transmitter. Just build a VFO
straight for 10MHz, or double up from 5MHz (lots of 5MHz VFO plans in
all the handbooks) or triple up from 3.3x MHz.

Tim KA0BTD

That's how I'd do it -- probably by tripling from 3.3x MHz, 'cause then
I could use the same VFO for other bands. One could, in fact, just use
one of the Handbook designs with the right coil set and possibly a
capacitor switched into the VFO to pull the frequency down a bit.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com