Bob - Here are the documents, web links, and answers from QRZ Q&A. http://forums.qrz.com/showthread.php?290978-3SK121-FT-726R-70cm-module-Q01
AMSAT-BB -- December 23, 2001 (Joe Leikhim, K4SAT) http://www.amsat.org/amsat/archive/amsat-bb/200112/msg00609.html Toshiba 3SK121 -- TOSHIBA TRANSISTOR Dual-Gate, UHF, 10V, Idss>20mA, Up<4V Datasheet (largely in Japanese). http://www.datasheetcatalog.org/data.../499109_DS.pdf The Icom mast-mounted pre-amplifiers (AG-25, AG-35) use the dual gate 3SK121 Dual Gate FET. The 2 schematics/manuals for the Icom AG-25 and AG-35 units are at QRZ page. You will see Internet recommendations for the 3SK121 replacement on AMSAT and VHF/UHF DX discussion boards based on this usage by Icom. These two distributors indicated they had inventory of this Toshiba Dual-Gate FET. XS Micro http://www.xsmicro.com/rfq.php?pn=3S...&ref=octoparts and Express Electronics (UK) http://www.express-elect.com/ I have seen one Eastern Asia exporter (eBay Seller id: my_mkchan) based in Hong Kong offer a variety of Yaesu parts, including some hard to find (no longer mfg.) transistors. I have seen the European CF-739 or BF981 listed as a suitable substitute. When you substitute check Noise Figures and Gain for your application. BEWARE of Counterfeit (Fake) Semiconductor Parts from Asia ..... http://sound.westhost.com/counterfeit.htm === w9gb ----- Original Message ---- > From: Bob- W7LRD <[email protected]> > To: [email protected] > Sent: Wed, January 9, 2013 4:05:35 PM > Subject: [amsat-bb] here's a good one! > > Getting ready for a AO-7A pass, started keying the transmitter, I >noticed the computer monitor was blinking very nicely in time with the >cw, also the az and el indicators on the G5500 control unit were dancing around in tune with the cw. >In fact they danced in tune even with the power off. Tipped over >satellite tower, got out ohm meter, direct open through the 2M Icom >AG-25 preamp. Jumped around the now removed preamp and we're back in >business. Question...The relay contacts seem to be suspect. Should I >get parts and repair the AG-25 or get a better preamp, as I am going to >scratch some EME efforts off my bucket list. If you have a better 2M preamp "laying " around let me know. > > as always > 73 Bob W7LRD _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
