MOSFET 3SK87 K87 for Crystal Radio "Zero-Voltage-Threshold” Detector

Description

We are a great source for many of your litz wire and crystal radio part needs. Since 2008, we've sold more than 10,000 orders with excellent customer feedback. Please visit our eBay Store at
mkmak222_Litz Wire
to see what is currently available.
We have over a hundred types of litz wire in stock. They contain 5 to 1650 strands of AWG 48 to 28 (0.03 mm to 0.31 mm) wire. The litz wire's equivalent AWG are from 24 to 6.
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Here you are bidding on 3 pieces of
MOSFET 3SK87 (K87)
per item (as shows in first picture), use for Crystal Radio Detector. The brand is NEC
.
This MOSFET 3SK87 is in the small package. It has the code "K87" printed on the surface.
Traditional crystal radios are used mineral detector or semiconductor diodes to detect radio signal. In recent years amateurs discover that some “zero-voltage-threshold” MOSFET such as ALD110900 or ALD110800 can substitute the diodes in crystal radio without use a battery, only need to add a coil between the souse gate and ground.
In recent years some Chinese amateurs discover the other kind of MOSFET - 3SK143-Q (3DQ) can substitute the more expensive ALD110900 and have better performance. Recently, at a radio forum in China, some amateurs found that NEC's 3SK87 can be used to replace 3SK143-Q (3DQ), and the effect is very good too.
When the signal is strong, the transconductance of 3SK87 is slightly higher than 3DQ. When the signal is weak, the transconductance of 3DQ is slightly higher than 3SK87. That means, the 3SK87 is little better for strong signal and the 3DQ is better for weak signal.
In general, 3SK87 is a good substitute, at least it is easy to solder.
The MOSFET 3SK87 is not “zero-voltage-threshold” but very close to, so it still can detect very weak signal and have superb selectivity in the crystal radio. Another advantage is that the output impedance of 3SK87 can be as low as 1 to 3 KΩ (the ALD110900 is about 25 to 50 KΩ), so you can directly connect the low impedance headphone to the crystal radio output connectors, don't need to use an impedance matching transformer. With the small Ni-Zn R40C1 Ferrite Toroids you will be possible to make a good performance pocket sized crystal radio.
http://www.ebay.com/itm/151443734224?ssPageName=STRK:MESOX:IT&_trksid=p3984.m1561.l2649
https://www.ebay.com/itm/NiZn-Ferrite-Toroid-R40C1-45x26x8mm-for-High-Q-SW-Barron-Crystal-Radio-Coils/153125692676?hash=item23a700a504:g:OIcAAOSw6tNbZMwC:sc:USPSFirstClass!94587!US!-1
For build the AM, SW and FM crystal radio with
3SK87,
please search "
The RadioBoard Forums
" on google and read all interesting articles about “
3SK87
” and “
R40C1
” in
Crystal Radios section.
http://theradioboard.com/rb/viewtopic.php?f=2&t=9360
http://theradioboard.com/rb/viewtopic.php?f=2&t=5959
Please e-mail any questions you may have before you order.
Please make payment arrangements within 3 days. I accept PayPal only.
Payment is expected within 10 days when place an order, or item will be released for sale.