I have accidentially made all sorts of mismatching the output from my OPA2674 and never have blown it. Running audio with Ozy/Janus and more than 1W rf-output. Maybe the reason is that you have overdriven the audio input.
Gerd, DJ8AY -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Pete Ferrand Sent: Wednesday, December 10, 2008 4:16 AM To: Ahti Aintila Cc: flexradio@flex-radio.biz Subject: Re: [Flexradio] blown SDR-1000 final opamp Ahti: Thank you for taking the time to reply. My radio has the OPA2674 and that is what it had originally. The issue is not one of a short circuit, but most probably one of dealing with a high impedance load which would send the voltage up beyond what the part can handle. At least that's what I'm guessing; I'm not sure of the correct troubleshooting procedure for this kind of fault. My hope was that someone has figured out how to make the circuit more robust but since yours was the only reply and there's no mention of it in the archives I suppose that hasn't happened. 73, -Pete WB2QLL Somers, WI -----Original Message----- >From: Ahti Aintila <[EMAIL PROTECTED]> >Sent: Dec 9, 2008 4:54 AM >To: Pete Ferrand <[EMAIL PROTECTED]> >Cc: flexradio@flex-radio.biz >Subject: Re: [Flexradio] blown SDR-1000 final opamp > >Pete, >The very old SDR-1000 units have OPA2677 as the final amplifier and >cannot stand short circuit. The newer radios use OPA2674 that has >internal short circuit protection. Anyhow, ask Flex people directly, >they know better the difficulties with some of the first production >units. > >73, Ahti OH2RZ > >On 09/12/2008, Pete Ferrand <[EMAIL PROTECTED]> wrote: >> >> Some months ago I blew the final opamp in my 1W SDR-1000 whilst >> matching it to a linear. Wasn't happy about that but since I >> accidentally hooked up the attenuator resistors wrong I wasn't too >> surprised since the rig saw a very high impedance. Worked fine ever >> since. >> >> Unfortunately I'm less happy about blowing the amp this morning, >> about a half year after that first incident, whilst trying it on six >> meters for the first time. Without the linear which doesn't cover >> six. Just wanted to see if I could work a couple locals. As far as >> the MFJ-269 showed there was a perfect match into the ATU but when I >> increased the power beyond about a tenth of a watt output the opamp >> popped again. >> >> Besides the time and money aspect, the circuit board clearly can't >> take a lot of parts replacements. >> >> Has anyone figured out how better to protect this part? Or some >> better solution. This is a four stack including the rfe board, older >> version with nylon spacers. >> >> Thanks. >> >> -Pete >> WB2QLL >> Somers, WI >> >> >> >> >> _______________________________________________ >> FlexRadio Systems Mailing List >> FlexRadio@flex-radio.biz >> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >> Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ >> Knowledge Base: http://kc.flex-radio.com/ Homepage: >> http://www.flex-radio.com/ >> _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/
