2SC458 Replacement Clarification (Kenwood KA-6000)

[MarcD]

Hello Everyone. I am planning on restoring an old Kenwood KA-6000 and have read probably a 100 threads on the dreaded 2SC458LG replacements and my head is spinning rapidly (although I've learned a lot so far). It seems a common replacement is the KSC1845, although some here on the AK say these may cause oscillation and to use the KSC1815 instead. But then I noticed reading the Kenwood manual that there are various "flavors" of the 2SC458's used. Most are "2SC458LG (B) or (C)". Some are just "2SC458B,C". But two (2) of them on the Pre-amp board are "2SC458LG (D)".

Looking at the datasheet, the 2SC458LG (D) version has the highest hfe of 250-500.



That brings me to the KSC1815YTA (readily available at Mouser), which states the Y version has an hFE classification of 120-240. I don't think the GR's or L's are available anymore.

Is it going to be an issue to use the KSC1815YTA's due to a lower hFE?

If I were to use the KSC1845FTA, also readily available at Mouser, in which application do I need to worry about Oscillation issues? (i.e. Main Amp, Pre-amp, ?).

Which is a better substitute ? Or do I select based on each application listed (B or C vs D)? Or something different altogether? (I've considered 2SC2240BL's but these are only available on eBay and I know most people's opinions on buying on eBay).

Any help is greatly appreciated. Not sure if this should be posted here or in the Kenwood thread, but figured I'd start here.


Thanks.
Marc

 

[tarior]

The gain of KSC1845F is 300-600. It's not too tough to sort through a batch of them and come up with a couple of pair above 400, which should be more than adequate. It would be great if 'E' or 'U' were available, but, alas...

 

[avionic]

great if 'E' or 'U' were available, but, alas...

 

[jheu02]

One reason many go with the KSC1815 is the collector current. 458 is 100mA, 1845 is 50mA, 1815 is 100mA. So, if you're not sure of the current going through the transistor, the "safer" bet is to use the 1815.

 

[tarior]

Don't tease.

 

[mcdoug3721]

The challenge/concern about replacements for the 458 and oscillation are more likely about it's frequency (ft) of 230 mhz. The 1845 collector current of 50ma is too low whereas the 1815 is 150ma with an ft of only 80 mhz. Depending on the circuit this may or may not be a problem. Diodes Inc. has a few high speed transistors to consider.

Compare Products​

Comparison of products

Product Info.
Image:
Check All:
Mouser Part #:	522-ZTX694BSTZ	522-ZTX694B
Mfr.'s Part #:	ZTX694BSTZ	ZTX694B
Manufacturer:	Diodes Incorporated	Diodes Incorporated
Description:	Bipolar Transistors - BJT NPN Super E-Line	Bipolar Transistors - BJT NPN Super E-Line
Lifecycle:	-	-
Datasheet:	ZTX694BSTZ Datasheet (PDF)	ZTX694B Datasheet (PDF)
RoHS:	Details	Details
Specifications
Brand:	Diodes Incorporated	Diodes Incorporated
Collector- Base Voltage VCBO:	120 V	120 V
Collector- Emitter Voltage VCEO Max:	120 V	120 V
Collector-Emitter Saturation Voltage:	500 mV	500 mV
Configuration:	Single	Single
Continuous Collector Current:	500 mA	500 mA
DC Collector/Base Gain hfe Min:	500 at 100 mA, 2 V, 400 at 200 mA, 2 V, 150 at 400 mA, 2 V	500 at 100 mA, 2 V, 400 at 200 mA, 2 V, 150 at 400 mA, 2 V
DC Current Gain hFE Max:	500 at 100 mA, 2 V	500 at 100 mA, 2 V
Emitter- Base Voltage VEBO:	5 V	5 V
Gain Bandwidth Product fT:	130 MHz	130 MHz
Height:	4.01 mm	4.01 mm
Length:	4.77 mm	4.77 mm
Maximum DC Collector Current:	500 mA	500 mA
Maximum Operating Temperature:	+ 150 C	+ 200 C
Minimum Operating Temperature:	- 55 C	- 55 C
Mounting Style:	Through Hole	Through Hole
Package / Case:	TO-92-3	TO-92-3
Packaging:	Reel	Bulk
Pd - Power Dissipation:	1 W	1 W
Product Type:	BJTs - Bipolar Transistors	BJTs - Bipolar Transistors
Series:	ZTX694	ZTX694
Standard Pack Qty:	2000	4000
Subcategory:	Transistors	Transistors
Technology:	Si	Si
Transistor Polarity:	NPN	NPN
Width:	2.41 mm	2.41 mm
Ordering Information
Stock:	11,629 Can Ship Immediately	6,026 Can Ship Immediately
Factory Lead-Time:	8 Weeks Estimated factory production time for quantities greater than shown.	40 Weeks Estimated factory production time for quantities greater than shown.

 

[MarcD]

Thank you everyone for your responses.

If I stick with the KSC1815Y do I need to worry about the gain being too low (120-240) where the original 2SC458D (only in two of the many locations) had an hFE of 250-500?

Thanks again.
Marc

 

[mcdoug3721]

Report back and let us know

 

[tarior]

Thank you everyone for your responses.

If I stick with the KSC1815Y do I need to worry about the gain being too low (120-240) where the original 2SC458D (only in two of the many locations) had an hFE of 250-500?

Thanks again.
Marc

It will be fine.

 

[MarcD]

Thank you! That's the response I think I'm going to go with. For now, anyway. Any further input from anyone is still welcome and appreciated.