[amsat-bb] Re: G5500 az el issue resolved!
db at db.net
Wed Jul 27 06:19:10 PDT 2011
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
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
- db at FreeBSD.org db at db.net http://www.db.net/~db
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