bf199 equivalent

[pitpat]

Hi guys, i need some help finding an equivalet for the bf199 pnp transistor for my hameg 103 oscilloscope
https://www.datasheetarchive.com/pdf/download.php?id=e1ec0cc83cd2410ebf459526a2f35b17b44785&type=O&term=BCS49.
I've read on an old tread that the bc547 npn will also work. is it true??
Thanks

[Andreas]

Hello,

the BC547 has a different pin out and lower band width.
Depending on the application it can work.

On the other side: there are still some manufacturers which deliver the part with the original specs (CDIL) eg. sold here:

https://www.reichelt.de/hf-npn-to-92-transistor-25-v-100-ma-350-mw-bf-199-p5433.html?&nbc=1

with best regards

Andreas

[pitpat]

Hi Andreas thanks for the help, the transistor should be for the y-preamp according to the schematics, ill'ask to my local supplier before ordering.

[Yansi]

THT components has started to become quite difficult to find whenever anything tiny bit special is required, like this.

The modern replacement could be something like a MMBTH10, you could use a small adaptor board to give it some "legs" so it will look more like the original one.

[Andreas]

Hmm,

in the schematic I see "sel." below the BF199 writing.
So obviously you need either paired (together with the other BF199) or some other special non data sheet parameters.

with best regards

Andreas

[pitpat]

My bad, i've sent the wrong part of the schematic (confused 701 with 101 that also is a bf199  ), from what i see  the 701 is part of the crt drive circuit.
Now the thing is if the transistor is shut open why the crt works? i've got no trace but in component tester mode i see trace and results...

[pitpat]

Full schematics in here https://cdn.rohde-schwarz.com/hameg-archive/HM103_englisch.pdf