Transistor HFE Ranking...Help?

[zachomega]

Anybody have any information on what the letters after the transistor model number mean?  I was told this has to do with ranking the transistor's gain. 

I'm specifically looking at 2sc644R and 2sc828Q but I'd like to know more about this in general. 

Any help would be greatly appreciated.

-Zach Omega

[petemoore]

http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?OpenForm
  I go to NTE, that only tells what they think about it compared to what they have, and if they have something 'similar' or close, but generally the first 4 lines at the top of their cross ref. data sheet cover compatability on 90%...data sheet on your Q is better if you can or need to find it.
  It's a good barometer to sound by socketing a transistor position, then trying out say a HG/LN Si NPN to a General Purpose NPN to a Low Gain NPN to a Ge NPN [some mods to bias ge maybe necessary.
  NPN / Si / HG/LN
  Tells that it's good in most neg gnd circuits, Si, High Gain Low Noise...which is generally great, especially in certain circuits that like HG in thier stages, and others where LN is good to have. In something like Nurse Quacky transistor gain and type can make a profound difference.
  Anybody have any information on what the letters after the transistor model number mean?  I was told this has to do with ranking the transistor's gain. 
  Those are coded #'s, mostly just to tell one type from another, the code follows no ratio/correlation to gain, just a system to ID Q types.

I'm specifically looking at 2sc644R and 2sc828Q but I'd like to know more about this in general. 
  Then google '2sc664R data sheet' / '2n5089 data sheet' '2n5088 data sheet' and so on...and see what comes up. Most of these transistors have numerous Mfr.s or suppliers, at least ones with very similar performances in the Si NpN line.
Any help would be greatly appreciated.
  Just looking through catalogues for part #'s...or schematics w/texts helps find the interesting part #'s, 2n4401, 2n2222, BC_ _ _to google for data sheets, NTE"s usually quicker, close enough to accurate for most stuff, socket the rest and do your best.

[zachomega]

Thanks for the reply...I found information on the 2sc828Q...But no real luck on the 2sc644R.  I have a 2sc644R and it measures pretty high so I figure based on the ranking of the 2sc828, the 2sc644 should probably be more like 300hfe.  Just guessing...

Anyway, the purpose of this excercise is as follows.  I am planning on possibly building a Bee Baa clone and I noticed I have two schematics.  One specifies using 2n5088 or 2n3904's which are common and the other specifies the 2sc828Q and 2sc644R.  The 2n5088's and 2n3904's tend to have gains of over 500 while both of the other transistors are considerably lower gain. 

I was curious as  to how that would tonally affect the Bee Baa.  Anyway, it is looking like I have some good substitutes for all of the transistors. 

-Zach Omega

[petemoore]

I was curious as  to how that would tonally affect the Bee Baa.
  With more than one transistor circuits it ~gets increasingly harder to tell which one[s are having what effect[s.
  I have't looked at the BeeBaa lately.
  Plugging Ge's in where Si's were may result in:
  More difficult to bias
  Smoother Distortion Tones
  More noise
  Less desirable 'something else'

[zachomega]

It is all Silicon in the Bee Baa...And the transistors I have are also silicon.  I have some good transistors for the 2sc828 and the 2sc644...But as I mentioned before, I believe the stock units to be considerably lower gain than the 2n5088 or 2n3904 substitutes.  We're talking a gain difference from as little as 50 upwards to about 400+.  I'm sure the units used in the Bee Baa originally were probably not too tightly grouped for tolerances so it might be a wild goose chase, but I would like to try and make the thing true to its design.  Maybe I'll socket the transistors and give it a try that way.  I don't usually socket silicon parts...or GE parts for that matter...

Do those breakaway headers work best or just use a clipped IC socket? 

-Zach Omega

[petemoore]

  A good Si is a good Si, they do differ, mostly in gain, BC's sound most 'differe'nt of all the Si's I've heard [listening to 'comparable gain' si's].
  Since you're attending to the gain, you'll probably figure out an optimum gain structure for your BeeBaa.
  I can't remember the last time I found a 'bad' Si that hadn't been somehow previously damaged. They all did pretty much what they're supposed to do, some slightly different/better for the application than others.
 
 

[zachomega]

Hmm...This is interesting...How do you feel that the BC's differ from the 2n's or 2sc's? 

I've been pretty taken with the 2sc transistors because they are readily available and extremely cheap...However, I do have quite a few BC transistor varieties in my parts box. 

-Zach Omega

  A good Si is a good Si, they do differ, mostly in gain, BC's sound most 'differe'nt of all the Si's I've heard [listening to 'comparable gain' si's].
  Since you're attending to the gain, you'll probably figure out an optimum gain structure for your BeeBaa.
  I can't remember the last time I found a 'bad' Si that hadn't been somehow previously damaged. They all did pretty much what they're supposed to do, some slightly different/better for the application than others.