tomizett
Active Member
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.
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.