homebrew
Allan Ross
equivalents for tubes. If anyone can point me towards any sources
of this information, I would appreciate it very much.
73 Al VE3DMR
WB3U
There were several articles on converting tube gear to solid state in one
of the major ham magazines in the early 70's. The articles took the
conversions a step at a time, with the approach of wiring the revised
components onto the tube socket pins when possible. I even remember
that the author of one of them had converted his Super Pro and claimed
significant performance improvements.
I don't have these articles anymore and I'm not certain which publication
they were in. If anyone has this series, I'm also interested.
73,
Jack WB3U
DB Wilhelm
>
> alr...@bmera223.bnr.ca (Allan Ross) wrote:
> >I would like to find some design data for building solid-state
> >equivalents for tubes. If anyone can point me towards any sources
> >of this information, I would appreciate it very much.
> they were in. If anyone has this series, I'm also interested.
> 73,
> Jack WB3U
From the Ham Radio magazine index published Dec 1973, I found the
following:
Converting a vacuum tube receiver to solid state p. 26 Feb 69
Short circuit p. 76 Jul 69
Converting vacuum tube equipment to solid state p. 30 Aug 68
Fetrons, solid state replacemnents for tubes p. 4 Aug 72
Pentode replacement p. 70 Feb 70
I had a listing of similar stuff in QST a while back, but I don't
know where I put it. Maybe someone with access to a composite
QST index can dig it out for us. I would also like to have
the references.
A long time ago (back in the 70s) I did successfully convert a
receiver (SX-99) to all solid state. It worked like a champ
after I cured all the gremlins due to the feedback in the IF
stages. More recently I reworked an old BC band command receiver
to cover 1.5 to 2 MHz and replaced the tubes with 40673 MOSFETS
and MPF102 FETs. Works like a champ. Never did get the AGC and
product detector put into it though. Maybe someday when I have
time, but alas, no source for the 40673 - RCA quit making them.
Does anyone have a stockpile? I'm interested in about a dozen,
73,
Don W3FPR
Michael T Decerbo
DB Wilhelm <w3...@nando.net> wrote:
> alas, no source for the 40673 - RCA quit making them.
> Does anyone have a stockpile? I'm interested in about a dozen,
Ditto here.
Better yet, is there a recommended replacement? I have a few
schematics for projects I'd like to try that call for the 40673, but
the only transistor cross-reference I have access to doesn't list it...
73,
Mike
N1FYO
--
Michael Decerbo -- 474 Memorial Dr Cambridge MA 02139 -- 617-225-7564
WB3U
>
> alas, no source for the 40673 - RCA quit making them.
> Does anyone have a stockpile? I'm interested in about a dozen,
There are a large number of Japanese N-Channel dual-gates that should
substitute very well for this device. Audio service companies use these,
mostly as replacements in FM receiver front ends.
I believe one of the common numbers we used was a 3SK140, but I've
been out of the industry for a number of years. You should be able to verify
a few suitable numbers with a local audio/video technician.
73,
Jack WB3U
Artur Jedrusyna
You can try MOSFET's of BF 900 - series,manufactured mainly by
Philips,Siemens and Telefunken. I think that BF 961,963 and 964 are
the best equivalents [suitable for VHF].If you want to try something
above 200 MHz, try BF900,or 960 or 966 [966S is better].
Artur Jedrusyna
Technical University of Wroclaw,Poland
jedr...@ime-1.ime.pwr.wroc.pl
// Wroclaw - the place where Silvius Leopold Weiss lived ...
Jon D. Garner
: In article <3q93r5$3...@misc1.microserve.net>, ja...@pinetree.microserve.com (WB3U) says:
: >>DB Wilhelm <w3...@nando.net> wrote:
: >> alas, no source for the 40673 - RCA quit making them.
: >> Does anyone have a stockpile? I'm interested in about a dozen,
All of my semeconductor cross referances say to use the
ECG222 MOSFET-N channel transistor as a replacement for the
old RCA type # 40673.
also the Thompson SK3065/222, Workman WEP905/222, and old GE MRO
GE-FET-4 are listed as replacements.
Booth, Thomas G
(Michael T Decerbo) wrote:
>
>
> DB Wilhelm <w3...@nando.net> wrote:
>
> > alas, no source for the 40673 - RCA quit making them.
> > Does anyone have a stockpile? I'm interested in about a dozen,
>
>
> Better yet, is there a recommended replacement? I have a few
> schematics for projects I'd like to try that call for the 40673, but
> the only transistor cross-reference I have access to doesn't list it...
>
> 73,
>
> Mike
> N1FYO
>
> --
> Michael Decerbo -- 474 Memorial Dr Cambridge MA 02139 -- 617-225-7564
Try using an SK3050 or a ECG221 in place of an old RCA 40673.
TGB
\\ The opinions expressed herein are my own. //
Tom Randolph
In article <3q8enp$n...@senator-bedfellow.MIT.EDU>, mi...@athena.mit.edu (Michael T Decerbo) writes...
>Better yet, is there a recommended replacement? I have a few
>schematics for projects I'd like to try that call for the 40673, but
>the only transistor cross-reference I have access to doesn't list it...
Here's a list I made up a few months ago. You can still get dual-gate MOSFETs,
but they ain't cheap. It might be easier to look up an equivalent ckt that
doesn't use one of these. I don't have a Japanese FET book, so I don't have
specs for any of the 3SKs, so I dunno whether they'd make a good 40673
substitute.
-Tom R. N1OOQ rand...@est.enet.dec.com
Dual-Gate MOSFETs
=================
These are still available for a price, even the old standby 40673. The bargain
MOSFETs these days are:
Type Price Where
===============================
3SK39 $1.33 MCM Electronics
3SK73 1.52 MCM Electronics
3SK74 1.95 RF Parts
3SK45 2.70 RF Parts
NTE221 2.85 Ckt Specialists
3SK72 2.93 RF Parts
3SK51 3.25 MCM Electronics
Also available:
Type Price Where Type Price Where
=======================================================================
3SK73 $3.73 RF Parts 3N212 5.95 RF Parts
NTE222 3.90 Ckt Specialists 3N213 5.95 RF Parts
3SK40 3.93 RF Parts 40673 5.95 RF Parts
TA7274 3.99 MCM Electronics TA7150 5.99 MCM Electronics
3SK40 3.99 MCM Electronics 3SK48 6.04 MCM Electronics
3N200 5.90 Ckt Specialists 3N201 9.50 MCM Electronics
3N204 5.95 RF Parts 3N200 ? RF Parts
3N211 5.95 RF Parts
DREW DIAMOND
>Does anyone have a stockpile? I'm interested in about a dozen,
>73,
>Don W3FPR
The NTE222 is a pretty good replacement for the 40673. Also MFE201, MFE301
and MFE131 if you geat 'em.
Drew, VK3XU.
>
TANTONR
Newark.
GL es DXOM.
michael silva
for 10) and MFE-211s for $1.42 ($1.06 for 10). I'm assuming these are
the same as the 3N2xx/MPF2xx parts, but my transistor book doesn't list
them so I couldn't swear to it. These prices seem almost too good to
be true, but I have all the dual-gate FETs I'm likely to need so I
haven't ordered any. Their number is 800-543-4330.
Mike, KK6GM
chuck adams
and I have a supply of house numbered critters and have been letting
them go for 3/$1 USofA and charging only $0.55 for postage and handling,
but I don't want to be doing this for a living. I really have a job.
These critters are light, so I think I can get a dozen or so in an
envelope with the critters wrapped in Alum. Foil. I do static protection
steps to keep from zapping them and my source has them in Aluminum foil
lined box. I don't have the facilities or the time to test each one,
but they should be OK. I'm not making anything on this to pay for my
valuable time.
Here are the stats:
Ye Ol Motorola manual says:
MPF131
N-channel Dual Gate MOS Field-Effect silicon transistor
depletion mode transistor designed for VHF amplifier and
mixer applications.
RF amplifier @ 60 and 200 MHZ
Max voltage , drain-source = 25 volts
Max current, drain = 30 ma.
Max power dissipation = 350 mw.
gate 2 ___ drain
<======/ \======>
| |
<======\__o/======>
gate 1 source
top view
NOT TO SCALE
(must I tell you)
info above from Kaye Hartman, KD8EK
And in another email I got:
MPF131 - Depletion type dual gate MOSfet with diode-protected gates
Speced as RF AMP @ 60 Mhz and 200 Mhz
Dot on plastic package indicates SOURCE lead, going counter-clockwise
from there: DRAIN, GATE2, GATE1.
Max ratings
Volts-drain-source 25
Drain Current 30 ma.
Ta= 25 degrees C 300 mW (hey its QRP!)
Gate 1 to source cutoff voltage -4.0 vDC
Gate 2 to source cutoff voltage -4.0 vDC
Zero-gate voltage drain current Idss = 3ma min, 10ma typ, 30 ma max.
Forward transfer admittance 8000 umho min, 20,000 umho max
this is biassed at Vds 10vDC, Id=10ma, 1Khz
Ciss = 4.5 pf typ, 7.0 pf max
Coss = 2.5 pf typ, 4.0 pf max
Crss = .023pf typ, .05 pf max (in-circuit capacitance usually larger than this)
Noise figure typ max
60 Mhz 2.5dB 5.0dB
200 Mhz 3.0dB 5.0dB
Power gain (common source)
60 Mhz 20dB 27dB
200 Mhz 17dB 20dB
Used as a R.F. amplifier, Gate 2 is usually set at about 4 v D.C. (unless you
want to apply A.G.C. to it).
This I got from Glen Leinweber.
It may do in a pinch as a replacement and is certainly much cheaper. Only problem:
I have to flatten the leads to get them mailed in an envelope. :-) Again, I don't
want to do this for very long and will do it until the supply runs dry. I don't
take checks and the bank doesn't sell MOSFETs. :-) It's a problem of time
to drive to same, etc. Green stamps OK, but email me first to determine if I am
going to have enough. There are only a few thousand of these still around.
I'm in the callbook.
dit dit
--
Chuck Adams K5FO CP-60 ad...@sgi.com
Michael Black
various suggestions for replacements for 40673 MOSFET's.
What might be important to note is that the 40673 might not
have magically been a great device, but was used in so
many published projects because others had already used them.
When someobody wanted to build a new project, they'd look
at what others had used, and saw that 40673 in common use,
and decided to use it since it must be good or why was it
already chosen.
I remember my first MOSFET's, and they were not 40673's. I
can't remember if I chose something else because I couldn't
get 40673's or because I wanted to find something cheaper.
I looked in a data book, and there were 40841's that looked
nearly as good. So I used them.
The point to all this is that if you can't get 40673's, maybe
the way to go is look through the catalogs until you find
MOSFET's listed, and then check their specs to find something
suitable, instead of looking in a cross-reference guide and then
trying to find a designated replacement for the 40673.
I came up with an interesting source of MOSFET's just last fall,
though I haven't gotten around to using them to see if they
are good or falsely numbered.
It's in those "FM Boosters" that seem to be readily available.
I'd seen them, and passed them by due to cost. Then I saw them
selling for under two dollars in a couple of places. I bought
one out of curiosity. Figured I'd find a bipolar transistor;
maybe I'd be lucky and find something like a 2N5179. I opened
it up, and found a MOSFET, in the 3N200 series if I recall
correctly. I went back to the store, and bought all that they
had (unfortunately, it was a few days later and some had already
been bought), at a dollar each. Good price for MOSFET's. If
anyone sees these FM Boosters (that's for receive, not xmit!)
at a low cost, it might be worth looking into them.
Michael VE2BVW
--
| InterNet: Michae...@juxta.mba.org
| Standard disclaimer: The views of this user are strictly their own.
DB Wilhelm
replacements. I have been offered a box of 80 of the critters.
I will have lots of fun using them. There seems to have been a
lot of interest here, I wish simolar fortune to any others.
73,
Don W3FPR