Need a few obsolete part numbers

Damn, looks like I got excited too soon. Here's what Bryan wrote in response:

So what gives? Are the NEC GaAs FETs obsolete too? Is there any reliable supplier of genuine parts still? Is there any other alternative?

Clifford Heath.

How about Dee Electronics, 1350 pieces of the NE25139 (sot-143 package) available,

Other dual-gate depletion-mode GaAs MOSFETs: Toshiba 3sk240 Renesas 3sk239A Nec 3sk299 Infineon cf739

Enhancement mode: Toshiba 3sk292

I passed your message to Bryan, who responded:

its still also obsolete. SOT-143 is > much larger and the cost of re-layout, BOM changes, engineering testing, qualification and authority recompliance > would normally outstrip the (usually inflated) cost of the parts themselves many times over. This is a typical

the U73 variant. 100% of parts

not appear on the Infineon web site.

I find it strange that in a situation like this, it's not economical for *someone* to make a suitable part. Sigh.

Clifford Heath.

I'm beginning to wonder if Brian, in a situation like this, isn't a bit off base, applying rules suited for mainstream components to end-of-life niche parts. What's wrong with a partial reel, if you can order full reels from DigiKey if that's not enough? Surely you two are complaining about how the market is no longer snapping up the discrete GaAs MOSFET offerings, which must mean they've found better parts for their purposes. Perhaps they've decided the small extra bit of SNR available from a MESFET stage, over a microwave linear IC, isn't worth the trouble of a bunch of discrete parts.

SQ-10a Teledyne Philbrick op amp

-- Boris

Are you saying there's a replacement part available from Digikey? Or that he shouldn't bemoan the obsolescence of a part for which no alternative of equivalent or greater performance is available, even allowing for a complete redesign of the receiver? Nothing short of a custom chip, made of available parts, cannot beat the performance of his design... makes it hard for the little guy...

Well, when you have a receiver that's a key element in international competition (amateur radio direction finding and radio orienteering), sensitivity, dynamic range, and noise floor - considering the need to stay within a low-power (hand-held battery-powered) budget - are at a premium :-).

Clifford Heath.

Use a 6SN7GTB instead.

Cheers! Rich

What about a 01A??