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Re: Amplifier transistor substitution.

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Cursitor Doom wrote...
>
>On Sat, 18 Mar 2017 19:03:54 -0700, Winfield Hill wrote:
>
>>  Sylvia, as mentioned, those are low-capacitance high-voltage video
>>  transistors.  All the rage when CRTs were in heavy use, but dropped
>>  like a rock thereafter. 
>
> Win, could you possibly post a few part numbers
> for these devices here, please?

 What, you want to know what's in my secret stash?!!
 200 to 300V video transistors are pretty amazing.
 They made broadband high-voltage amplifiers, taking
 advantage of the low-capacitance deflection-plate
 load, only a few pF.  Most are gone now, along with
 the CRTs they powered.  But a few are still here.
 To find them I type TO-126 into my 'Everything'
 search engine, maybe adding a voltage like 300V,
 and check their availability on Octopart.

 Whoa, I see we can still buy Toshiba's 2SC5460,
 800V, 2.2pF.  Quest has inventory, $0.39, qty 50.

 KSA1381 pnp 300V 3.1pF 7W Fairchild $0.25 Digi-Key
 KSC3503 npn 300V 2.6pF 7W Fairchild $0.26 Digi-Key
 KSA1142 pnp 180V 4.5pF 8W Fairchild $0.25 Digi-Key
 KSC2682 npn 180V 3.2pF 8W Fairchild $0.11 Rochester
 KSC5026 npn 800V 35pF 20W Fairchild $0.45 Digi-Key
 MJE350 pnp 300V 6.4pF(meas) 21W, multiple sources
 MJE340 npn 300V 4.1pF(meas) 21W, multiple sources

 The MJE340 and MJE350 datasheets don't mention
 capacitance, so I had ignored those for years.
 But eventually I measured two ON Semi parts,
 Cob at 100V, and was pleasantly surprised.
 There's also the MJD340 and MJD350 in DPak.


-- 
 Thanks,
    - Win

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Thread

Amplifier transistor substitution. Sylvia Else <sylvia@not.at.this.address> - 2017-03-18 20:27 +1100
  Re: Amplifier transistor substitution. "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-03-18 10:41 +0000
    Re: Amplifier transistor substitution. Cursitor Doom <curd@notformail.com> - 2017-03-18 11:13 +0000
    Re: Amplifier transistor substitution. bitrex <bitrex@de.lete.earthlink.net> - 2017-03-18 18:15 -0400
      Re: Amplifier transistor substitution. Sylvia Else <sylvia@not.at.this.address> - 2017-03-19 12:44 +1100
        Re: Amplifier transistor substitution. Winfield Hill <hill@rowland.harvard.edu> - 2017-03-18 19:03 -0700
          Re: Amplifier transistor substitution. Sylvia Else <sylvia@not.at.this.address> - 2017-03-19 13:14 +1100
          Re: Amplifier transistor substitution. Cursitor Doom <curd@notformail.com> - 2017-03-19 14:11 +0000
            Re: Amplifier transistor substitution. Winfield Hill <hill@rowland.harvard.edu> - 2017-03-20 06:20 -0700
              Re: Amplifier transistor substitution. Cursitor Doom <curd@notformail.com> - 2017-03-20 23:26 +0000
  Re: Amplifier transistor substitution. Phil Allison <pallison49@gmail.com> - 2017-03-18 04:08 -0700
    Re: Amplifier transistor substitution. Sylvia Else <sylvia@not.at.this.address> - 2017-03-18 22:42 +1100
      Re: Amplifier transistor substitution. "Benderthe.evilrobot" <Benderthe.evilrobot@virginmedia.com> - 2017-03-18 22:01 +0000
  Re: Amplifier transistor substitution. Sylvia Else <sylvia@not.at.this.address> - 2017-03-19 16:34 +1100
    Re: Amplifier transistor substitution. Cursitor Doom <curd@notformail.com> - 2017-03-19 14:13 +0000
      Re: Amplifier transistor substitution. John Robertson <spam@flippers.com> - 2017-03-21 08:34 -0700
        Re: Amplifier transistor substitution. Cursitor Doom <curd@notformail.com> - 2017-03-21 18:18 +0000
  Re: Amplifier transistor substitution. Sylvia Else <sylvia@not.at.this.address> - 2017-03-20 13:28 +1100
    Re: Amplifier transistor substitution. Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-20 10:59 +0200
      Re: Amplifier transistor substitution. Sylvia Else <sylvia@not.at.this.address> - 2017-03-21 10:57 +1100
  Re: Amplifier transistor substitution - fixed. Sylvia Else <sylvia@not.at.this.address> - 2017-03-22 19:33 +1100

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