|TRANSISTOR TESTING - general review of my inventory of JFETs and DG
MOSFETS (mainly).. doing some testing
to determine the health of the inventory --- 12 Jan 2014 (UPDATED: 29
|First up for testing are the 12 Dual Gate Mosfets that I ordered Dec 2013.
The supplier is an ebay supplier. I have found the company to be one of
my favorite suppliers and they started selling the 3N211 dual gate mosfet
in 2013 at a price that was a bit lower than everyone else's price on ebay.
Anyways.. I bought 12 for my inventory. The idea would be that I test them
and sell them at a slight markup in price. I would sell them for about $7.50
to $8.50 -- in that range after testing to be sure they working (first of all)
then secondly..that they provide good amplification in the RF Amplifier
and perhaps a mixer stage of the FT301 test radio.
Well my initial findings were not good actually. 2 out of the 12 did not work
at all. You can tell right off the bat when the dud part is in the RF amplifier
transistor socket. The receiver is very quiet. Only a faint signal is
apparent. (Some residual feedthrough).
When a healthy 3N211 is inserted in the socket..the signal is loud and the
S meter is around S6. Test oscillator is the IC-718 turned down to 1 watt
and transmitting into a dummy load.
SO..IN MY TESTING THERE ARE LEVELS OF TEST.
1) The most basic level. - Does it work? GO or NO GO. I am beginning to
think that these large manufacturing outfits in the orient dont actually test
their parts..at least not all of them. Perhaps they just do spot testing.
Perhaps they dont test at all in some cases.
2) A more detailed PERFORMANCE TEST- IF you look at my articles titled
DUAL GATE MOSFET SHOOTOUT -- see my index home page
www.hamelectronicsmagazine.com for the whole table of contents
concerning what I do here.
In the article DG Mosfet Shootout.. I test samples of my inventory and I
measure the amplification by closely examining the S meter of my receiver
while using a test oscillator.
One of the key specifications of a JFET or Dual Gate Mosfet is the
transconductance figure. -- I dont go into the testing that deeply.
I did some reading lately and I may try doing that..AND/OR -- I may go and
buy a test instrument that can give me this data.
My current test instrument you see in the pictures..seems to give
consistent readings and is a good approximation in real world conditions.
I am a technician myself. I graduated a 2 year Electronics Engineering
Technician Program at Algonquin College in Ottawa and most of my work
was in the government in the Life Cycle Material Management of small
components such as resistors, transistors, ICs, capacitors and similar
small components which were classed as "consummables" -- and throw
away items..ie if a component goes bad..you throw the old one away and
insert a new one.
|BEARING DOWN TO DO SOME WORK!
|Its not all fun and games in my retirment years. Im 60 years old now and took an early retirement option in 2005. One does need to exercise the brain
and do some actual head work. I have an active mind and I do find I need to exercise it and I dont like video games. Another thing I used to do was I
took a course in QUICK BASIC -- Quick Basic computer language. I also studied other computer programming and now I use this html type of
software to do my web pages. I dont write html code but rather with YAHOO SITEBUILDER it is a very easy drag and drop kind of way of making web
pages. That way..one can concentrate on the content of the pages rather than try and struggle with the software to make it.
|I had bought a group of 2sk19GR jfet transistors from ebay ..I think I bought 20. So I am testing them now because I have an order to fill for someone.
I sell them at a fairly low price of $2 each. Anyways..In the testing I found one which did not test good at all. It showed up as a resistance from pin one
and 2 and an open circuit from pin 2 to three. -- ALL the other jfets tested ok but there was a variance of a significant nature. What I did is I grouped the
jfets for this fellow (he wants 8 of them) and I took the 8 that tested consistantly average ..all about the same.
Good tested Motorola 3N211 for $7.50 each.
40673 dual gate mosfets I sell now for $5.75 and they are tested
the 2SK19GRs I sell for $2 each (currently) --
2N3819s I sell for $1.75 each tested individually.
MY PRICES are most reasonable for tested parts
Usually..people order small amounts ie 5 JFETs or 10 dual gate mosfets and I can send them
in a padded envelope for $1.50 within Canada and $3 to USA locations and an average of
$5.20 to other places overseas ect.
I can supply small amounts of tested parts to you for hobby use and experiments ect.
I get a few orders every week and it gives me a good activity.
DEC 29th 2014 - I have actually epanded a bit and now have a commerical web site
and new email address for parts orders. email me email@example.com - same
low prices - same good helpful advice - Im just ramping up a wee bit to make a few
extra dollars here and there. 73 earl ve3ab
I also buy old collections of parts. I prefer the old parts from the 1970s, 80s and early 90s.
Back then..I dont think there was as much counterfeit stuff and junk like there is being made
One fellow I know (who is in a technical trade) told me he doesnt mind counterfeit parts as long
as they work!! -- Well.. problem is ..as Im finding through my more detailed investigations ..that
some of the parts are pure junk. See my article concerning the 40 - 2sc2075 transistors. All 40
are in my stock quarantine. JUnk that wont be sold. So..if you come to me for your parts..at
least you will know they are working parts.
|I sell --- TESTED COMPONENTS --
The commercial side of the house is my
other web site: www.nettyelectronics.com
CLICK HERE TO VISIT my little commercial
site (sales of tested components)
and www.earlandrews.com (mirror sites)
|3N211 dual gate mosfets pictured above. I bought 12 of them from a seller on ebay from SHENZHEN, China. To be fair.. Could have been just a
bit of bad luck ..a bad lot of parts.. stuff happens.. but I am now reconsidering how and where I buy stuff from and I am going to start more
rigorous testing..ie instead of just spot testing..I am going to start testing components before they go out the door and Im going to start
testing components with a bit of burn in time..in my radio equipment. For example..the parts that do test good like these 3N211s -- I will put
them in the FT301 radio and either do some operating with it and/or I will cycle it through some sort of stressfull conditions..ie flicking on and
off the power swith on the radio and the power supply and receiving high level signals pinning the S meter and see if any fail while being
pushed a bit hard.
Another thing I am doing as of now..as of results of testing this past 2 months or so ..is I am phasing out buying parts from overseas like China
and Hong Kong. I am going to instead try buying domestic parts ..perhaps from people getting out of the service field or people who are
retiring and down sizing their collections of old parts. --SO IF YOU HAVE ANY OLDER PARTS..I WOULD BE INTERESTED IN BUYING THEM
PLEASE SEND ME AN EMAIL _ here is my email address: firstname.lastname@example.org
|ARE THESE DUAL GATE MOSFETS DELICATE?? YES AND NO ACTUALLY! To try and abuse one of the dg mosfets in my collection..I plugged it
into the transistor socket wrong 3 out of 4 times. IE: Each time I rotated the part 90 degrees and plugged it in. 3 out of the 4 times the dg
mosfet would be plugged in wrong.
It took the lickin and kept on tickin! Just like an old Timex watch commercial. The part was still working after undergoing the wrong
connection plug in 3 times 3 different ways. -- I have yet to handle a working dg mosfet and have it fail because of some random static burst
that might have happened. The basement shop is not dry and seems like very little static. Also..I ground myself periodically when handling
electronic devices on my bench. I just reach over and touch metal on the spectrum analyser or other piece of gear in the vicinity. I never
hear a static snap. These modern dg mosfets have some zener diode protection internally. HAVING SAID THIS: why put the part in danger.
Keep yourself grounded and if you have a ground strap why not wear it . You can wear it on your ankle if you like.
|My tester can be seen on the bench in front of me.
These can be bought from ebay for about $20 or so.
They are likely built in China. There are some very
interesting hobby circuits on ebay and testers.
I am going to buy some more sophisticated test gear in
the near future. A more complex transistor tester that
measures leakage and many other parameters of
transistors runs about $200 and I have it in mind.
For home/hobby use..the tester I use ($20 or so) will
check ESR and Capacitance as well as test JFETS and
IF you are going to buy stuff off ebay ie parts..then a
tester is a good idea. You can test your parts and
perhaps even test them before writing your ebay
EBAY (NEGATIVE FEEDBACK GIVEN) re the 3N211s
I left my first NEGATIVE FEEDBACK on ebay just today.
It was concerning the 2 out of 12 lot of dual
|UPDATE: 28 FEBRUARY 2014- I bought a slightly better tester for testing transistors and diodes and ESR ect. Shown below: bought from ebay in
January and just got it in the mail yesterday. Im quite pleased with this new tester. Some chinese characters I dont understand on the screen but
there is enough English symbols and numbers that make it very useful and easy to operate. Has some graphics with the display which helps
Identify parts and find out a little bit about what is actually inside the enclosure (what basic type of part it is and basic architecture).
|This tester comes with flexible leads and that was a useful feature when trying to do some analysis of BF981 dual gate mosfets. One of the
good ones is pictured above. I ordered a batch of 30 from a company that is really big component distributor on ebay (UT SOURCE).
The batch of 30 Dual Gate Mosfets (BF981 were all defective). If you want to read about it..I wrote an illustrated web page at this LINK HERE -
This being said: UT SOURCE has been very co-operative and Im sure they want to get to the bottom of this situation as well. They gave me an
address to mail back my defective parts and they assured me they will re-emburse me for both the parts and my postage as well.
THEY DID RE-EMBURSE ME FOR THE DEFECTIVE BF981S.
LINK TO MY START PAGE ..www.hamelectronicsmagazine.com
www.earlandrews.com (they are mirror sites).
LINK TO MY NEW SITE : www.nettyelectronics.com (IT is a small business
web site) -- TESTED GUARANTEED COMPONENTS THAT YOU DONT HAVE
TO SECOND GUESS !
73 Earl VE3AB
|16 percent FAILURE RATE 2 out of 12 of the 3N211s ordered from
UT Source in China. I may order again in the future ..perhaps they
will improve their screening and testing by then.
|NEW ARRIVALS at Netty Electronics (my
little electronics store) 40823 Dual Gate
Mosfets (tested good) -$5.75 each
Quantity of 30 just arrived - while
|BELOW: a transistor that sort of fell apart!
I like the older parts from the 1980s. I BUY OLDER PARTS FROM HAM RADIO
COLLECTIONS. I much prefer the older parts because they seemed to be much more
consistent and a person could trust them off the shelf. Some of the Chinese Parts are
OK but some seem to be cheaply made. Its almost like they are being produced in a
big rush or something! BF981 Dual Gate Mosfets seem to be particularly
inconsistently manufactured. I received a whole order of garbage parts. You can read
about the BF981 bad parts at this link here.
IF YOU HAVE SOME OLD PARTS TO SELL for a reasonable price ..just email me at
my new commercial email: email@example.com - Id be pleased to talk to you
and give you an estimate. I take donations of old parts too and I do trades as well.
I could trade you some radio parts or accessories for your components. I am most
reasonable and NO PRESSURE FOR SURE ! Im a retired civil servant who took early
retirement option and now I just do this to keep busy. A hobby business and my new
hobby business site is www.nettyelectronics.com -
|1 out of the 20 2sk19GR Jfets tested bad. 5 percent failure rate. BEFORE I SEND OUT MY PARTS THAT I SELL ( I only do
small orders as a general rule)-- I test the parts individually.
|what a bummer !! BF981s - 100 percent failure rate!!
|When I worked for the Defence Department up here as a civilian for about 18 years..I was in Nato Cataloguing and Item
Management (Material Management) of small electronic components such as ICs (microcircuits, transistors, and resistors and
other small components). The MIL SPEC components would be tested BURNED IN FOR 1,000 HOURS in what industry called MIL
STANDARD 883. Later.. they did an accelerated burn in for only about 160 hours but at a higher temperature which they calculated
to be equivalent to the 1,000 hours burn in.
Id be very interested to see how some of these commercial parts being cranked out of China would compare to the Military
parts. Military MIL SPEC RESISTORS come in failure rate levels of .001 percent failure rate level. I have some of these MIL SPEC
resistors now that I have bought surplus.
As per above article.. the parts I have tested were not in any jig for testing or burn in (under load).. they were just tested with
simple test instruments and were showing bad failure rate (INFANT MORTALITY)- without ever being put into a circuit !
NOW YOU CAN SEE WHY I AM LOOKING TO BUY OLDER (NEW OLD SURPLUS) OR EVEN USED PARTS FOR MY LITTLE BUSINESS
VENTURE: NETTY ELECTRONICS -- 73 AND Thanks for stopping by.
|MIL SPEC PARTS BY COMPARISON
|Introducing : NETTY ELECTRONICS (on line store)