[NLRS] Sick 736

[Dr. Gerald N. Johnson]

On Tue, 2006-08-01 at 06:57 -0500, Chris Elmquist wrote:
> 
> On Monday (07/31/2006 at 10:31PM -0500), John Oehlenschlager wrote:
> > 
> > 
> > My Yaesu 736 is acting very strange with a number of "birdies" on 2 and 
> > 432. They occur about every 10 to 15 kHz.  Any suggestions?  The operators 
> > manual and the detailed maintenance manual are about as useful as congress. 
> > Any help would be appreciated.
> 
> I am getting birdies on my 736 which are being conducted into the PTT
> control jack on the back of the radio (the DIN plug that carries all four
> PTT signals from each band module) via (soon to be changed) unshielded
> cable that connects to the PTT inputs of my external amplifiers.  This
> cable is picking up RFI from nearby computer equipment and conducting
> it into the radio that way.  It doesn't come in via the antenna jacks
> because I have terminated those with 50 ohm and the birdies are still
> there, strong as can be.  Disconnecting this PTT control cable, kills
> the birdies.
> 
> Jerry's point about power supply noise is good too.  That seems like a
> reasonable rate for an (older) switching supply.  It is also a reasonable
> rate for video so you could look for something coming out of a computer,
> VCR, cable TV system, etc.
> 
> Good luck!
> 
> Chris NØJCF
> 

It would be really handy to check for birdies with a separate radio,
like a handheld to localize their source. That could prove the 736 OK,
just hearing its environment or prove the source is internal to the 736.

The 736 power supply noise is significant, especially on the power line.
When my 736 is turned on, my X power line remotes don't work and one
time it turned one of them on.

-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer