Friday, October 16, 2015

Belthorn (Bell Thorn) III Moved to 20 Meters

Belthorn III Moved to 20 Meters and Making QRP Contacts!

Several months ago I resurrected a project that was built some 12 years ago and updated the rig with a Si5351 + Arduino Controller, a color display and a new box. This radio had some innovations like using a Motorola Gain Block amplifier (CA2818C) which happens to be a 24 VDC device and led to embedding a DC to DC Convertor (MeanWell) into the project. It is a single conversion at 9.0 MHz and uses a GQRP Crystal Filter. The Arduino sketch includes a built in tone oscillator to provide a 988 Hz tone for tune up purposes.
The RF AMP is an IRF510 but I wished I had used a real RF Transistor like a 2SC3133 as the output on 20 Meter is slightly less than on 40 Meters. I am seeing about 7 watts on 20 Meters where I got close to 10 Watts on 40 Meters.
Now that I have a new beam antenna I decided to move the Belthorn III to 20 Meters and one of the first QRP contacts was with N0TUX/KH6. Thanks to Ron Taylor G4GXO for the original Belthorn design. Thanks Ron -- the Belthorn still perking along after 12 years!
There are two videos and the second is of the QRP contact. Check for more info on the Belthorn III.
Pete N6QW