SR-2000 VFO UPDATE 014A
This update corrects a number of design problems in the VFO
Birdies and Spurs on this web site will be defined as RECEIVE Birdies and TRANSMIT Spurs.
1. Reduces the 3rd harmonic of the VFO by 40db. This corrects a number of serious and nuisance problems.
2. Corrects the 30 cycle transmit to receive offset.
3. Reduces Birdies and Spurs 40db to acceptable levels.
4. Equalize the S-Meter and transmit drive when using the HA-20.
5. NOTE: The diagram --- SR-2000 51E --- has the change area and lines color coded Blue.
This VFO change corrects 1, 2, 3, and 4 above. #7 is a photo of the wiring.
6. Spectrum analyzer Video of VFO harmonics. SR-2000 VFO HARMONICS
7. Under-chassis view of VFO wiring changes, one closeup and one global.
8. Sweep view of added 3 pole elliptical low pass filter used to clean up VFO third harmonic. Note the two markers represent the low and high end of the VFO range. Sweep photo of filter