Hi Phil, 100% agree. I'm not going to risk a substitute - especially in the crystal oven.
Unfortunately, check out http://www.americanmicrosemi.com/Shipping/ and see they will charge me US$69.99 which is AUS$100 for posting a single $8 transistor! The cheapest I have found so far is down to US$22 postage for a single transistor. Regards, 2009/8/11 phil <fort...@bellsouth.net>: > > ----- Original Message ----- From: "Dave M" <masond...@comcast.net> > To: <time-nuts@febo.com> > Sent: Monday, August 10, 2009 10:10 AM > Subject: Re: [time-nuts] HP 106B quartz frequency standard...the story > > >>> Thanks for that! - I do have a number of the 5254L units and one of >>> them is now being eyed off for organ donation. So thanks to all offers >>> for the 1854-0003. >>> >>> The 2N1701 in a T08 is my next quest... >>> >>> 2009/8/10 Dave M <masond...@comcast.net>: >>>>> >>>>> Hi all, >>>>> >>>>> Latest update. >>>>> >>>>> With some help and phone calls from Bill the fault seems to have been >>>>> isolated. I have removed Q11 from inside the oven and it is cactus. Q9 >>>>> is also very suspect so I'm going to replace that for good measure. >>>>> >>>>> Q9 is a 2N1701 in a T08 package. Thanks to various people I should be >>>>> able to track one down. Q11 is marked as 1854-0003 and that's an HP >>>>> internal number and all I know. Might have to substitute that one. >>>>> >>>>> After all this I have some quality photos and can knock up some good >>>>> descriptions of the repairs and the 106B internals if anyone is >>>>> interested. Any websites hanging around that want to take what I have? >>>>> >>>>> Regards and thanks to all! >>>>> >>>>> Jim Palfreyman >>>>> >>>>> >>>> >>>> >>>> Jim, the 1854-0003 is a pretty common HP part in older eqpt. ?If you >>>> have >>>> junked 5245L counter handy, it's full of them, especially in the decade >>>> counter PCBs. ?If you don't have one handy, I have an assembly here with >>>> 8 >>>> of them on it. ?If you like, I can send it right away (if you're outside >>>> the >>>> USA, you pay postage). >>>> >>>> Dave M >>>> masondg44 at comcast dot net >>>> >>>> I went to a bookstore and asked the saleswoman, "Where's the >>>> self-help section?" She said if she told me, it would defeat the >>>> purpose. >>>> >> >> Jim, >> The NTE sub for the 2N1701 is the NTE152, available from Mouser and many >> other suppliers. According to the datasheet, it's in a TO-220 case. If you >> want to try to find a sub in a smaller package, here are some of the >> pertinent specs for the 2N1701. >> NPN Silicon >> Vcbo = 40V >> Ic (max) = 2.5A >> Pd = 25W >> Hfe = 20-80 @ 300ma/4V >> Vsat = 1.5V @ Ic=300ma, Ib=30ua >> Iceo = 750ua @ 60V >> Ft = 350KHz >> >> Dave M >> masondg44 at comcast dot net > > I would not use a "cheap" general replacement transistor in a direct coupled > unit unless it was absolutely positively the last one on earth. Many vendors > have that 2N1701 in stock from 7 to 8 bucks American. We have repaired > thousands (no exaggeration) of units that all that was wrong is where > incompetent technicians used general replacement transistors rather than the > originals in direct coupled amplifiers. > http://store.americanmicrosemiconductor.com/2n1701.html > > Phil > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.