[Yaesu] FT890 strange behavior

[Paul]

Excellent advise.

de Paul, W8AEF

-----Original Message----- 
From: Earl Morse
Sent: Thursday, July 11, 2013 6:52 AM
To: Michael Tortorella
Cc: yaesu at contesting.com
Subject: Re: [Yaesu] FT890 strange behavior

Rather than pile $25 worth of ferrite and filters on it why not take a 
divide and conquer systematic approach to resolving the problem.

Start with the supply.  Can you draw 20-30 Amps out of it with just a plain 
resistive load?  If not, the supply may be defective without even adding the 
RF part into the equation.

Next add the radio without all the microphones, CAT interfaces, external 
speakers, etc connected.  Transmit into a dummy load at a low power level. 
Do you notice the issue?  Check all bands.  If the issue is still non 
existent increase power and repeat checking all bands.  Check CW and 
Modulated modes.

If the issue is still not recurring start adding the microphones, head 
phones, speakers etc back into the equation and recheck functionality to see 
what it takes to make that power supply fold up.

The final stage will be adding the antenna and transmitting full power with 
everything hooked up.

Once you know exactly what it takes to make the supply fold up it is going 
to be much easier to determine the exact fix.  Adding a ferrite bead (what 
mix??) to attenuate common mode currents when you are uncertain about which 
frequencies or which cables are even causing the issue (1.8-30 MHz is a big 
chunk of spectrum)is more of an exercize in how lucky you are rather than 
how good you are.

Good luck with the process.  Let us know how it comes out.

Earl
N8SS