|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
|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.
|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.
|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
|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
are not ABSOLUTELY SCIENTIFIC..but I
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.
|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
|I was sold out of 40823s but NOW
I HAVE THEM AGAIN. I have
about 30 in stock and I sell them
for $5.00 each.
** I buy old surplus parts and my
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