Breadboard project, DSB SC 20m QRP

[VE3GZB]

I had some success working QRP on 20m, managed to make some pretty good distance on just 1 or 2 watts.

So after a phone call from my friend VE3AWA, I decided to start putting a vintage QRP DSB SC rig together, just for kicks. Working on it in the evenings for just an hour or two at a time while Yvonne is watching evening TV.

The basic design comes from this:

http://www.r-type.org/static/bmod.jpg

Still have some minor teething issues and refinements to iron out, but on the whole everything is working as it is supposed to be. I've got a suitable audio coupling Xformer on order through my boss, he gets his stuff at Digikey and a push pull coupling Xformer for audio runs about $4.

The balanced modulator/power amplifier (a pair of Osram PT2 pentodes) behave as they are supposed to, though I did have to iron out a 147MHz parasitic last night. Adding a pair of 1.5-7pF neutralizing caps AND 47 Ohms to the control grids and plates killed the parasitic just fine.

I did cheat on the filament supply. Since these tubes aren't available at your friendly radio shack, I went with individual voltage regulators on each tube.

A lot of the parts were salvaged in the past from old Heathkit stuff.

Just wanted to share,
Thanks and 73s
geo VE3GZB

[VE3GZB]

Two more JPEGs of the rig.

[W4AAB]

Looks good!! I worked a WA3 somewhere around Annapolis, MD a few years ago using solid-state 6m DSB. Somewhere in the early 1970's 73 Magazines, there is a 10m QRP DSB transmitter.Good to see someone building. That is why I belong to this list.
                                   Joe W4AAB

[VE3GZB]

Yea, it's fun! And most refreshing!

73s geo VE3GZB