DUAL GATE MOSFET SHOOT OUT.. I put about 10 various types of Dual Gate Mosfets that I have in my
collection and that I sell to hobbyists to the TEST. The clear winner was the 3N211
Recently..I picked up this Motorola Portable Test Set..
Model 1056..actually I think it might be the 1056B. For $20 I
figure I couldn't go wrong.

The thing that really caught my eye was the crystal test
capablity. I thought..(when I bought it) that it might work
well for overtone crystals..but Im not sure now! Anyways..I
used it tonight in my so called Dual Gate Mosfet Shootout!

Dual Gate Mosfets were very popular in homebrew articles
in QST in the 1970s and 1980s. My HW-7 Heathkit QRP
transceiver (simple DC receiver) uses a dual gate mosfet
in the front end. My Ten Tec Argonaut 505, 509 and 515 all
use a DG mosfet in the receiver RF amplifier stage and the
505 uses a DG mosfet as a mixer as well.
My FT301 transceiver (circa 1978 to 1983 or 84) uses 2 dual
gate mosfets. One as the receiver  RF amplifier and one for
the receiver mixer. Both DG mosfets are on the RF board
which is handy for testing as it is a plug in circuit board.
The radio I was using (FT301 analog version) has transistor
sockets for each of the dg mosfets and I use it often to test
my dual gate mosfets. Tonight..I was plugging various dg
mosfets into the RF Amplifer stage. The original FT301
design calls for a 3SK40 device. I have a few around but I
prefer to use 3N211s as they provide superior gain and
work better. You will see this demonstrated on this page
with the S Meter readings I obtained.  
Note: I am still working on testing some more DG Mosfets and I will be doing this again
tommorrow..but I thought Id go ahead with the article now and put it on my web site. It
is a work in progress. 18- Sept 2013.
The crystal I was using was 7.002 mhz. It provided a good enough
signal on the harmonic up in the lower cw band of 10 meters. I did all
the S Meter readings on 10 meters. The antenna for the FT301 was
a piece of hookup wire on the bench.
Here I start the test with using Motorola SFE 1612s. I have some commercial samples and I feel they are just a wee tad bit better than the 3N211s.
I use 2 of these SFE1612s in my FT301. One in the RF amp stage and one in the mixer stage. I dont sell the SFE 1612 because I cannot seem to
buy any. I only have enough for me!!
Above..I switched over to the recent 3N211s that I bought from a distributor in China. I only ordered 10 this time. Priced slightly below the American and
Greek distributors on ebay with lower shipping. - As you can see..the S meter is slightly lower than my favorite dg mosfets. Not all that much but a bit.
The ever so popular and still widely available RCA 40673! Not all that impressive..but it works. I bought some of these 40673s not all that long ago and I
sell them for $5 each. -- For my money..I would spend the extra $2 for the 3N211.
Here I am back to the 3N211 again..but this time -- I selected from a different batch that I purchased earlier this year. This batch was branded T.I.
and Malaysia. They are good performers as well. -- I might add at this point..so far..I have not come across any real duds! I am testing at HF
though and perhaps if I were at the upper frequency limits of these devices..I might see some fall off in performance..who knows??? I have seen
videos and read about phoney CB final transistors that dont give as much power out put as they should and their performance drops off at the
higher frequencies approaching 11 meters.  
Here is the 3N202. I dont have many of these devices. I might have bought some from a QRP mailing list I belong to or perhaps at a ham
radio flea market.
A motorola device with what looks to be an in-house part number. I have about 15 of these devices. A solid S4-- just a wee tiny sliver better than the 40673.
I might mention..that all these devices I am testing today are drop in replacements and pin for pin layout the same.
Next is the 3SK45. I only have a few of these around. About the same as the 40673 ..or maybe a wee bit better.
A bit of a surprise to me is the NTE222 I tested next. I only have a few of these around..but this one tested  close to S7..just like a 3N211. Perhaps this one
is a 3N211 -- just with an NTE part number. The NTE 222 can be used to replace a number of different DG Mosfets.
Next was a 3SK40. This is what is in the FT301
manual as the correct part to be used on the RF

This one was a used pull and it tested S-0.
So..I colored it red and will discard it later.
Above is pictured the RF board in one of my Yaesu FT301 transceivers. NOTE: there are two dual gate mosfets on
this board and both are in sockets. Usually..only one of the dual gate mosfets are in a socket and the other one is
hard wired (soldered on the board). WHEN I TEST MY DUAL GATE MOSFETS; (before I sell to public I do spot testing
of the stock I buy to ensure they work properly); I use this FT301 and pull out the board (RF UNIT) and plug the DG
mosfet under test into the socket for Q102 the RF gain stage for the receiver portion of the FT301.
MY RF BOARD in one of my FT301s actually has 2
transistor sockets. One for the RF gain stage and
one for the mixer stage. I put an SFE1612 in both
stages just to try it out and my receiver was much
improved as far as signal strengths. So I'm going
to keep it this way. Pictured below is the S meter
reading and
RELAX!! -- its only a pellet gun.. a 22 caliber single shot rifle. I gave up hunting years ago. I still fish however!! I actually gave up hunting about
the same time as I got my ham ticket in 1972.
Here I test the 40823 on another day. OF
COURSE..the results are sort of
relative. Even if I move my hands and
arms on the bench..the s meter may
change readings a bit so.. the results
did enough testing and comparisions to
say the results are pretty close to real
world expectations and results.

These 40823s and another type I was
selling this spring and summer 2013 for
$3 each as a bit of a promotion. I bought
them from ebay at a real good price and
I should have bought more..BUT..I was
afraid they might have been phoney
parts. They work about as well as the
40673 which I sell for $5 each.
The 40673 registered S4 on the meter
but Im quite sure that the only reason
that the 40823 registered only S3 is
because I tested them on different days
and I had to hook everything back up
again and probably something was not
quite the same as the day before.

Whenever I have tried the 40823 in the
past..it seems to work as well as the
40673 (if not maybe even just a tad
better). The 3N211 is a better performer
My testing has only shown up one DUD dg mosfet. They can be damaged by static discharge ..and you should ground yourself periodically when
working with them. My basement shop seems to have a low or almost non existent static buildup..but I still ground myself periodically to the body
of a near by spectrum analyser when Im working with these items. -- IF you are in a hot dry static filled room with a carpet then I would recommend
keeping a ground strap on your leg or wrist. and use a static mat. The DUD ..dg mosfet..I color coded red with a marker. It was in a circuit previously
and probably got blown perhaps by either a spike or static burst or something. Almost all the newer dg mosfets are zener diode protected
INTERNALLY..but a strong static field can still damage the parts.
The 2 NEW types of dg mosfets are the SFE1612s that
someone sent me to try out. Id like to buy some. They
seem just a touch better than the 3N211s.
Below: the schematic of
the circuit for the dg
mosfet. I plugged the test
subjects in and out of Q102

One reason the DG mosfet
is in a socket is because
the RX in (from the
antenna) goes to one of
the gates and sometimes
static on the antenna can
damage the fet.
This isn't the first time I have tried various dg mosfets in the RF board of my FT301. I also tried a BF981 that I modified with radial leads to
allow it to be plugged in to the transistor socket. The BF981 was similar in performance to the 3N211 but maybe not quite as good. The
BF981 is quite readily available and fairly inexpensive (around $1.75 to $2) but it is a bit of work to mod them for radial leads. To see more
of the previous article concerning this-- go to this page LINK HERE
BF981 modded with radial leads
Hope you enjoyed the shootout!! 73 Earl VE3AB of hamelectronics magazine.com
(a free ham radio magazine which is almost commercial free and certainly is unbiased..and it is a hobby of
mine ..more than a business venture) .. Amateur ..like Amateur Radio.
Any money I make selling parts or doing the odd bit of service (at $10 per hour) goes to pay for the web
sites I operate and the shop supplies for all my experiments and tinkering projects..73 earl

TO THE HOME PAGE OF hamelectronicsmagazine.com -- 73 earl ve3ab
I cannot find any 4 pin transistor sockets so what I
do is I make my own transistor sockets out of these
40 pin sips that are readily available from ebay.

I sell them as well.
I was sold out of 40823s but NOW
about 30 in stock and I sell them
for $5.00 each.

** I buy old surplus parts and my
prices are
very very reasonable.

Id like to buy more surplus parts
to help other hams and
electronics tinkerers out.
Please feel free to send an email
and we can discuss with ZERO
pressure! 73
earl ve3ab email link
On ebay a fellow in USA is selling
these AMP Repair pins for printed
circuit boards. These little socket
pins are excellent and I have
started using these for dg mosfets
and transistors.

They work a bit better than the
machine SIP sockets for the lighter
guage wire leads.

For small amounts..I sell small
amounts of these repair pins to
hobbyists and restorers if you dont
want to buy 100 at a time.