Crystal Radio Impedance Matching Box Installation Kit KPB-02 from 200KΩ to 4Ω

Description

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Here your bidding on an especial design Audio Matching Box Installation Kit for Crystal Radio, they have 12 steps of input and output impedance from 200KΩ to 4Ω.
For detailed information about the
KPB-02
Impedance Matching transformer
,
please search "
The RadioBoard Forums
" on google and read all interesting articles about “
KPB-02
” in
Crystal Radios section.
This kit includes following components:
One KPB-02 Crystal Radio Impedance Matching transformer.
Two 1 X 12 rotary switch includes two knobs.
One 500K
Ω potentiometer with a knob and a 0.1 uF capacitor for Benny circuit.
Two ¼” mono speaker output sockets.
Four banana
sockets
and
plugs
.
One 4-7/8 X 3-1/2 X 2 inch plastic box
You only need to prepare some strong tape and appropriate size of screws & nuts to hold the
transformer on
plastic box, and some insulated wire for circuit wiring. The
rotary switchs only have 12 positions, so on the transformer you can choose 12 Impedance taps for input (for example from 200KΩ to 150Ω) and 12 Impedance taps for output (for example: from
40KΩ to 32Ω,
20KΩ to 16Ω, 10KΩ to 8Ω,
5KΩ to 4Ω
).
You also can order the KPB-02 Crystal Radio Impedance Matching transformer only in this link:
http://www.ebay.com/itm/KPB-02-Crystal-Radio-Impedance-Matching-Transformer-200K-to-4-Selectable-/162007211102
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: 4 X 3.5 X 3 cm
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
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!