With the success of our HBR-16 receiver project, we really needed a matching CW transmitter. So we "borrowed" the design of the Heath DX-60 and its matching HG-10 VFO and built one.

We incorporated all of our "wish list" items into the design, built in electronic keyer, sidetone (with audio fed into the receivers speaker or headphones and its own level control), transmit/receive switching, SWR bridge, low pass filter and receiver spoting as well as full metering.

Due to our desire to match the HBR-16 receiver that we had already built, there was no room for the 6146 final tube except under the chassis. So that's were it went. Putting the final under chassis required cooling, which explains the small exhaust fan on the rear of the chassis, as seen here. The raised box on the rear of the chassis houses the low pass filter and SWR bridge.

Combining three separate chassis boxes allowed easy shielding of the oscillator/buffer/modulator circuits on the bottom righrt (yes we have AM capabilities just like the original Heath DX-60, though we never have used it), the power supply on the bottom left, the final amplifier on the top right and the T/R switching on the top left.

Clicking on the images to the left will reveal the project close up. To see the transmitter's block diagram and schematic, click these links on the left.
Click on any picture to enlarge it
Our HBT-90 transmitter
The top of the chassis
The underside
The HBT-90 as built schematic
The HBT-90 block diagram