EMRFD Message Archive 6358
Message Date From Subject 6358 2011-06-01 20:57:51 billw77aaz UM2104C PIN DIODE I want to buy a Microsemi UM2104C PIN diode. Neither Avnet nor Future have any. Although I expect either will probably order one, does anyone have a pointer to a source that might have them in stock?
6359 2011-06-02 02:11:40 ha5rxz Re: UM2104C PIN DIODE Bill
I've tried the following
6360 2011-06-02 06:29:21 billw77aaz Re: UM2104C PIN DIODE Thanks for looking, Peter. I had already searched all of the usual sources. It's a very specialized device and expensive for "just a diode", so distributors probably don't want to keep them on their shelf gathering dust.
I was just hoping someone on this list would have beaten a path through the bushes ahead of me and know someone who keeps some on hand.
73 - Bill W7AAZ
6361 2011-06-02 07:14:04 popmedkoh Re: UM2104C PIN DIODE That's a very specialized part indeed! A two-lead part capable of switching 2.5 Kilowatts at frequencies down to 500 KHz or less (using rule of thumb of Usable Freq = 10 x 1/(carrier survival time). Carrier time in this part is 20 µsec min and 25 µsec typical. You might look at this eBay item:
This is a lot of 10 smd devices pulled from commercial radio equipment. Specs are only 1.5 KW and carrier time of 2.5 µsec good for maybe 80 meters. He used to have the 6 µsec part (I've bought from him and he's very reliable) and you could ask him if he has a part close to what you need. BTW what are you building? Perhaps you shouldn't let the TSA know about it!
73 David KE1LY
> Thanks for looking, Peter. I had already searched all of the usual sources. It's a very specialized device and expensive for "just a diode", so distributors probably don't want to keep them on their shelf gathering dust.
> I was just hoping someone on this list would have beaten a path through the bushes ahead of me and know someone who keeps some on hand.
> 73 - Bill W7AAZ
6362 2011-06-02 09:44:21 billw77aaz Re: UM2104C PIN DIODE Thanks for the pointer to Baruch's diodes. It was amusing to see people on eBay selling 1N270s and calling them PIN diodes.
I have some MA/COM UHF TX PIN diodes, should have known they'd have HF diodes, too.
I'm making a plain old tube amplifier, a 4CX1500B. Not even the legal limit, but chosen for its very low IMD (20 dB better than MOSFET). The long carrier lifetime is to preserve the low IMD of the amplifier down to 160m.
I've used current-driven vacuum relays to get <2 mS switching. I want to put a PIN diode in this one because even in an insulated wooden box I can still hear the relay clicking. And I had one die after a year of casual usage. So want to go PIN.
I measured a 6A100 rectifier and it has long carrier lifetime and low RF resistance when forward biased. But its capacitance is about 20 pF at hundreds of volts reverse bias. That's too much. A "real" PIN diode has a few pF of capacitance with only 12V reverse bias.
The MA/COM diodes have slightly lower dissipation rating than Microsemi, but lower RF loss. They kinda balance out. A MA4P4001B would work but Avnet says no stock for MA4P4001B HF diodes and minimum order is 300 pieces.
I bought something from Baruch a long time ago. I'll ask if he has anything in the MA4P4000 series.
6363 2011-06-02 15:33:38 Gian Re: UM2104C PIN DIODE Ciao Bill,
I have processed one of my usual purchase for 6x UM2104, specifying package C. I will inform you if these will be available.