This is amazing! Thank you!
Cant find any 2sa1084...can i replace them with 2n5401?
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MidnightArrakis
Well-known member
[known in some circles as a roach clip] -- Way back in the 60's and 70's.....I have had some -- GREAT -- times while being in some of those "circles"!!! It all started when I was going through electronics training school while in the Army. The military training instructors couldn't understand why all of the test equipment alligator-clips were all disappearing!!! >> PFFFFFFTTTTT!!! << -- Yeah.....well..........WE knew why!!! PFFFFFTTT!!! cough..... cough.....cough.....
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Fort Gordon?
MidnightArrakis
Well-known member
[Fort Gordon?] -- WOW!!! EXACTLY!!! Were you there also??? I was in what was called, "The United States Army South Eastern Signal School" (USASESS) for my training as a -- 31L20 -- or, in English, as a "Field Radio Communications Equipment Repairman". My training was from October 1969 to June of 1970, which I had heard was one of the longest A.I.T. courses within the Army. I can remember all of us -- regular -- soldiers always looking over at the next building over from ours because -- THOSE GUYS -- were going through "Cryptography" training and they had to go through all of these "hoops, loops and shenanigans" just to either enter into or even exit their building each day!!! It was weird!!!
What was also weird was.....my even being in the "Field Radio Communications Equipment Repairman" course because I was actually a member of The Indiana National Guard and -- NOT -- a "regular" soldier who was probably going to end up in Vietnam!!! As it turned out, I ended up.....of all places.....in Bangkok, Thailand working at a repair depot there repairing the combat communications field-radios that were used by the front-line soldiers who were calling in the air-strikes for our Vietnam combat soldiers!!! What a turn of events, huh??? One of my "best" memories from being over there is the fact that -- WITHIN TWO HOURS -- from when I landed at the Bangkok airport, I found myself having some great sex with some young "Pooyang" who found her way to my hotel room there in Bangkok!!! All I can say is..........their views on sex over there is a whole lot different than ours here in the States!!! YOW-WEEE!!!
I can even still remember Ft. Gordon getting a 1/2-inch snow accumulation in March of 1970 and the whole base going into shutdown mode!!! All of us guys from northern states (Indiana, Michigan, Wisconsin, Ohio, Vermont, New Hampshire, Maine, etc.) just laughing our asses off because "life doesn't shutdown" where all of us lived until the snow accumulation reaches >> 3-FEET << or more!!!
In some other thread on this forum, I gave a brief account of how 5 of us guys from Ft. Gordon all went "AWOL" one day in order to see Led Zeppelin down in Macon, GA by paying-off some other guy to go through all of the motions and routines -- TO MAKE IT LOOK LIKE WE WERE THERE -- while we were all doing a few "doobies" on our way down to see Led Zep later that evening!!! WHAT A TIME THAT WAS!!! And..........I even still have the -- front-of-stage -- photos from that concert with me!!! (NOTE: As a "side-hobby" within my life, I also did "concert photography" starting with The Beatles in 1964 and ending with The MOODY BLUES in 1994. I literally have -- THOUSANDS -- of photos of YES, Journey, Led Zeppelin, The MOODY BLUES, Bob Dylan, Blue Oyster Cult, U2, Aerosmith, Blue Oyster Cult, Pat Benatar, The J. Geils Band, Quicksilver Messenger Service, Uriah Heep, Prince, Jimi Hendrix, Grand Funk Railroad, etc., etc. from either being right there in front of the stage or from actually being on-stage off on the side-stage area or from behind the drums!!! So.....my concert going experiences were just a tad bit different than the regular concert-goer!!!).
So.....what were you doing there at Ft. Gordon???
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I was trained in army avionics commo equip repair 94L under B-company 73rd Ordnance. Fun times!
MidnightArrakis
Well-known member
You answered my post before I had finished it. You may want to check my posting again!!!
Ah I see, I think they merged your mos and mine into 94E.
But I got out in 2012, before the change over happened. I was at fort Gordon in 2006, and most of the partying I did was in Augusta. No concerts though. I did make quite a few civilian friends.
For all Schoeps style mic driver stages you may also use BC327-40, better obtainable in Europe. Dont care about cross references, better understand the circuit operating principle. Because BC327-40 (and the smd style BC807-40) are very cheap, hfe selection can be made. Buy 10 pieces and find 2 transistors with hfe matching at 10%. These transistors have a very low noise figure because at low operating currents (1..2 mA) noise is mainly generated by the base line resistance rbb. Dont care about the max operating voltage of 45 V. It is never reached in a proper Schoeps mic circuit..
BR MicUlli
BR MicUlli
... And at least in the original Schoeps circuit they have 6.8v zeners across the C-E junction anyway.
Actually AUDIO FREQ lives in the United States, it's more difficult to buy components from Europe
I tested 2 pnp A1015 transistors and one has an HFe of 302 and the other has 289. Is there an acceptable margin of difference, or do they have to match exactly?
Philbo King
Well-known member
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- Aug 15, 2023
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- 139
It's normal to have a large spread on beta values. If it meets the minimum spec it's generally good. A lot of resistors in an amp circuit are there to swamp out beta variations over temperature and from part to part.
I mean for matching them.
From my own experience, in the Schoeps topology the match should be better than 5%. Your two A1015 transistors measuring hFE 302 and 289 have 4.4% matching. They will work very well.
In basic after we took all of our tests, I was assigned 35E20 MOS (military occupational specialty) repair and maintenance of tank artillery aiming computers. I chose that electronics specialty because it had the longest school, and I wanted to burn up as much time stateside as I could to avoid the Nam. To my surprise they just awarded that MOS to me based on my civilian experience and assigned me to permanent party in a maintenance battalion at Ft Riley. While processing-in through battalion headquarters, the clerks who actually run the army, saw my test scores and pulled me out to work with them in headquarters instead. I ended up working as a 91B clerk/typist in S4 battalion level supply.
At Ft Riley KS we got some serious snow. The smart play for when a winter storm was forecast, was to make damn sure you got stranded off base, because all the suckers they could find hanging out in the barracks got stuck pulling KP and guard duty for all the missing troops smart enough to get off base.
The typical scam is to pay the company clerk to show you as present on the morning report, I knew one troop who took extra weeks of paid vacation that way, and when he ETS'd they actually paid him for over month of unused vacation despite him literally taking extra months over his brief tour. I only saw one guy get caught doing that because he paid the clerk to show him as present on payday, and the OD (officer of the day) distributing the cash, searched for him to give him his pay... oops.
I think my older brother (RIP), who was also drafted, did some time at Ft Gordon, and had a gig working inside a radio truck. He said it was more comfortable than sleeping on the ground in the field.
JR
