Crystal Radio Impedance Matching Transformer KPB-02 200KΩ to 4Ω Selectable

Description

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Here you are bidding on an especial design Audio Matching Transformer for Crystal Radio, they have 17 steps of input and output impedance from 200KΩ to 4Ω, due to their plentiful inductance of coil, they can be used as 400KΩ impedance transformer and still have good performance.
You also can order the KPB-02 Crystal Radio Impedance Matching Box Installation Kit in this link:
http://www.ebay.com/itm/-/152127000011?ssPageName=STRK:MESE:IT
Many crystal radio fans know the Bogen T725 audio matching transformer. The builders of quality crystal radios have found them useful as a matching auto transformer between the diode output and headphones. But the maximal impedance of T725 only can reach 40KΩ.
You may need higher impedance auto transformer if you want to build a better quality crystal radio. Some crystal radio fans in China are design, test and produce a new autotransformer for this target.
This transformer has 18 terminals , can be match from 200KΩ to 4Ω by 17 steps. They use high permeability ferrite magnetic core and easy to get plentiful inductance with this small
volume of core. The crystal radios output only have small electric current (from microampere to few milliampere), so we don’t have to worry about magnetic saturation in magnetic core.
The specs of this transformer are:
Dimension: L 40 X W 35 X H 27 mm
Pins length: 6 mm
Weight: 104 gram
Electrical parameter:
Pin No. -- Impedance -- DC resistance
14 -- 200 KΩ -- 3.55 KΩ
13 -- 100 KΩ -- 2.04 KΩ
12 -- 40 KΩ -- 810 Ω
11 -- 20 KΩ -- 479 Ω
10 -- 10 KΩ -- 253 Ω
9 -- 5.0 KΩ -- 170 Ω
8 -- 2.5 KΩ -- 113 Ω
7 -- 1.5 KΩ -- 80 Ω
6 -- 800 Ω -- 52 Ω
5 -- 500 Ω -- 37 Ω
4 -- 300 Ω -- 24 Ω
3 -- 150 Ω -- 12 Ω
2 -- 64 Ω -- 6.7 Ω
White wire -- 32 Ω -- 4.1 Ω
Blue wire -- 16 Ω -- 2.2 Ω
Yellow wire -- 8 Ω -- 1.4 Ω
Red wire -- 4 Ω -- 1 .0 Ω
1 -- 0 Ω -- 0 Ω
1 -- 0 Ω -- 0 Ω# E8 K: `
We compare the Bogen T725 and this
ferrite magnetic core transformer
in an actual measure, with
0.3V 1000Hz
sine wave signal input at 40K
Ω tap and a 300Ω resistor at 300Ω tap, the result shows the conversion efficiency are 83.5% and 94%. This small
ferrite magnetic core transformer
is 10.5% better than Bogen T725.
For more information about this
transformer, please use key word "
KPB-02" to search articles in
theradioboard.com
, or read the artical:
A Ferrite Magnetic Core Matching Transformer for Crystal Set
(
http://theradioboard.com/rb/viewtopic.php?f=2&t=4277&p=38595&hilit=mak1939#p37687
)
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. Buyer pays .50 (same if order two pcs ) for USPS shipping within the US. International buyer pay shipping for USPS First Class Mail.
It is time to clean up the electronic related items in my garage, please keep an eye out for my other eBay auctions! Thanks for looking!