Tube Testers
  Tube Tester Manuals
  Tube Sockets
  Our Buy List
  Ordering Info
  Return Policy
  Our Test Lab
  Contact Us

Tube Lists

  00 -- 3V4
  4-65 -- 6AZ8
  6B4 --6DZ7

  6E5 -- 6KZ8

  6L6 -- 6ZY5
  7A4 -- 11R3
  12A -- 12Z3
  13CW4 -- 35Z6G
  36 -- 1276
  1603 -- 5998
  6000 -- 8426
  8507 -- 9006
  A2426 -- ZM1000

 Special Tube Lists

  Western Electric
  Antique Tubes
  Transmitting Tubes

  Audio Preamp Tubes

  Audio Triodes
  Audio Pentodes

Popular Tube Quick Links

2A3 45
10 71A
6B4G 6A3
50 801
6A5 6BQ5/EL84
6CA7/EL34 6L6
7027A 7591
7868 6550/KT88
6V6 12AU7
12AT7 12AX7
12DW7 5751
7247 6DJ8
6267/EF86 6922/7308
6SN7/5692 6SL7/5691
Store Hours
Monday - Friday
9 am - 5 pm
Central Time

SND Tube Sales


Michael Marx
105 N. Division St.
Bonne Terre, MO 63628

Ham Call: WB0SND


7868 Tube List


Matching Tubes

Tube matching is required when 2 or more tubes are operated in push-pull in an output circuit.  This is especially important when the circuit is a fixed bias circuit and the tubes are operated at or even a little beyond their maximum ratings.  This is typical in audio amplifiers as  manufacturers would try to squeeze every watt of power out of the amplifier.  If you don't use reasonably matched tubes in such a circuit, you run the risk of destroying one or both tubes as you could never properly bias the circuit for both tubes.  They don't usually have to be EXACTLY matched; just within a few percentage points of one another.  Also, if you have a stereo amplifier which run the tubes in 2 pairs, IT IS NOT NECESSARY TO BUY A MATCHED QUAD!  2 matched pairs will be fine.  Tube tester matching is NOT normally effective matching because most tube testers operate the tube far below the normal operating parameters used in the amplifier.  Tubes that match at typical tube tester voltages will NOT usually be matched in the amplifier.  I use different types of test equipment to match tubes.  I normally operate the tubes at typical amplifier voltages and measure plate current.  Transconductance is NOT important when matching this way. 

Matching is available when I have enough tubes on hand to select from.  Plate current matching where available will add an additional $5 per tube.  Please inquire about matching for NOS and used tubes.  Matching is usually available on currently produced tubes like Russian tubes.


Type Description Price 
7868 RCA RCA Black Plate USA  New (NOS)  Earlier version of this tube made by RCA had black plates.  Where all 7868's are in short supply, these black plates are especially hard to find $60 ea
7868 RCA As Above, but USED TESTED GOOD $30 ea
7868 RCA RCA Gray Plate USA  New (NOS)  Later production RCA's had gray color plates.  Otherwise, they are the same as the earlier black plate version. $55 ea
7868 Sylvania Sylvania USA  New (NOS)  Sylvania made an excellent 7868.  Many 7868's were made by them.  They had the exhaust tip on the top of the tube unlike GE and RCA that had the tip on the bottom (between the pins).  This makes them look very cool. $50 ea
7868 GE General Electric USA  New (NOS)  GE's look a lot like RCA's with gray plates.  Exhaust tip is on the bottom like RCA. $50 ea
7868 Used RCA (gray), GE, or Sylvania USED TESTED GOOD $30 ea