On Wed, Jul 27, 2011 at 06:45:34AM -0400, Jeff KB2M wrote:
Thanks to all for the refresher on the 5500 repair. I replaced the 17806P (which I think has a 6v output) with a 7805. This fixed the problem. I had to recalibrate as my max readings in the SatPC32 rotor calibration routine dropped because of the assumed lower output voltage of the 7805 regulator. I
Put a pair of silicon diodes between the ground end of the 7805 and actual ground.
I was going to suggest this trick before, but thought you had already ordered a 7806. This will increase it to just about perfect. You might even get away with a single diode.
While you are in there, don't forget to bypass the input and output with a little more capacitance. The ceramic they have shown in the schematic is insufficient. The 7806 itself can start oscillating making a noisy racket all over HF and VHF. I used a 4.7uf since I had one lying around.
- 73 Diane VA3DB