Hi All,
I'm afraid it's another dull
"can you tell me what this is" thread.
I'm trying to identify the pictured transistor in order to repair a piece of equipment where a number of these devices have failed. It's a
SOT89 package (also known as
SC62 or
TO-243) marked
891 <newline>
29P. I have another example from a very similar piece of equipment which is marked
7C1 <newline>
29P, so I'm assuming that the 29P bit identifies the device.
What else can I tell you about it?
It's an RF power N-channel depletion mode JFET, from a piece of equipment specified to operate from 470 to 870MHz. When they are in circuit and working, they are powered from an overall supply of 12V and draw a drain current of about 430mA through their load resistor such that the transistor sees about 8V between D and S. At this bias level, the gate is between -1 and -1.2V (with S being grounded).
What have I found so far?
Nothing useful, searching by any or all of the part number and package.
Assuming that I might not be able to find an exact replacement, I've had a look around for other JFETs that might fit the bill. So far, I've found:
MAGX-000040-00500P (Macom)
MwT-1789SB (Microwave Technology/IXYS)
SHF-0189(Z) (RFMD)
XF1001-SC (Mimix)
I know that it's not much to go on, but what are people's thoughts on the viability of making a substitution? I'm not an RF guy, so I really don't know how application-specific these devices are. The circuit seems to be a single-stage common-source amplifier; this transistor is the only active device in the signal chain, the rest being a passive combiner network.
Thanks for reading and thanks in advance for any advice.