Brian, How is the diode connected in the iso box? I've made the mistake of putting it across the key line when it really has to be across the coil of the relay to suppress the back EMF of the coil. Even the little 12 volt coils produce a wallop when the circuit is opened.
If you have a 10X high impedance probe and a scope you can see the back voltage is a big number without the diode even with small coils. I'm familiar with RF loose in the shack. I burned out the input to my Tek 2712 spectrum analyzer a few years ago. Cost me $2200 to get it fixed as I need it for my broadcast measuring business. Has to have traceable calibration to be legal for the measurements so I had to pay the shot to Tek for the repairs. 73, Larry K2LT Brian Sherrod wrote: > On 5/20/06, Larry Taft <[EMAIL PROTECTED]> wrote: >> Brian, >> >> What is in the isolation box? I'm always looking for ways to do the >> control keying and changeover functions. > > Nothing more than a tiny 12v relay I was keying by grounding from pin > 7 & 15 with diode protection. > > >> As far as repair of the ULN2003A goes, I recommend sending the SDR back >> to Flex as it is all surface mount stuff on the board. They are >> skilled, reasonably priced and fast. Three out of three is good! Just >> had my SDR-1000 in for upgrades and repair. > > Okay Larry, thanks for that info! > > 73 Brian / w5ami > > _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
