[ARC5] JFET in ARC-5 TX oscillator socket

[Dennis Monticelli]

The RCA 3N128 is a single gate MOSFET where the gate is of metal (not
polysilicon as they are made today).  I don't think the gates had any form
of ESD protection back them so be careful with handling.  JFETs are more
rugged, have much lower 1/f noise than early MOSFETs, and have
characteristics that better mimic tubes.  When you put another gate on the
MOSFET, it makes for a more compelling device.

On Wed, Jul 8, 2009 at 5:34 PM, <mstangelo at comcast.net> wrote:

> Mike,
>
> Ah yes, the RCA 3N128. I remember when QST had a cover article about using
> that IGFET in a low drift VFO.
>
> You know you're getting old when you remininse about discrete
> semiconductiors!
>
> Take Care,
>
> Mike N2MS
>
>  ----- Original Message -----
>
> From: WA5CAB at cs.com
>
> To: mstangelo at comcast.net
>
> Cc: ARC5 at mailman.qth.net
>
> Sent: Wed, 8 Jul 2009 23:57:31 +0000 (UTC)
>
> Subject: Re: [ARC5] JFET in ARC-5 TX oscillator socket
>
>
>
> Lord, I don't remember.  I was either a Senior or a first-year Grad Student
> at the time.  Maybe 3N128?  That's an IGFET, isn't it.  They were brand new
> at the time.  I designed the circuits and wrote an IEEE student paper about
> it but never actually butchered the SP-110-LX they were to go into.
>
>
>
>
>
> In a message dated 7/8/2009 6:47:27 PM Central Daylight Time,
> mstangelo at comcast.net writes:
>
>
>
> I realized the tongue-and-cheek remark but you brought back memories of my
> early parts scrounging days. FET's were relatively new on the hobbiest
> market and I was lucky to find them surplus.
>
>
>
>
>
> Anyway , I found my old catalogues. Barry's "Green Sheet" has 1625 at $3
> each and 1626 for $1.40. G&G does not have the 1626 but has the more common
> 1625 at 50 cents each. He also has 6V6G's for 75 cents each.
>
>
>
>
>
> The only commercial JFET I know of in the $15 range are Crystolonics JFETS
> used in Active anbd Broadband amps.  JFETS are mostly small signal devices
> these days and are inexpensive. The power MOSFET's are the expensive one
> these days. Which JFET did you buy?
>
>
>
>
>
> Mike N2MS
>
>
>
>
>
> Robert Downs - Houston
>
>
> wa5cab dot com (Web Store)
>
>
> MVPA 9480
>
>
>
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>