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G8MNY > TECH 06.07.19 16:00l 36 Lines 1223 Bytes #999 (0) @ WW
BID : 11511_GB7CIP
Read: GUEST
Subj: Clip on QRM Probe
Path: IW8PGT<IZ3LSV<IW0QNL<JH4XSY<JE7YGF<GB7CIP
Sent: 190706/1353Z @:GB7CIP.#32.GBR.EURO #:11511 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (Updated May 13)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
Wanting to find which lead on a devices like TV & STB set up, has the most RFI
current it, I made a simple current probe from a clip in ferrite choke. It can
be used with a Rx or spectrum analyser. And for Tx RF work too, finding if
balanced line is balanced, coax line is really RF free etc.
THE CURRENT PICK UP
/~~~~\
QRM cable Hinge / /~~\ \ Locking
================= ùÃÄ´ ÃÄ´û Catch
:::::-¿screen Rx_________\ \__/ /
10 ())))_³____ Coax~~~~~~~~\\±±±±/
turnsÀÄÄÄÄÄÄÄÄÄÄ50ê Coax Heat Glue^ Coil
The clip on ferrite is about 2cm dia with a single
0.5ê 1T
1A============
:::::10T
())))_____100mA
³_________50ê = 0.5W = 5V = 74dBmV = 134dBuV
WHERE T MainsÄÄÄÄðÙ ðtest points ~~~~lof current into a 1/4 wave long T
See also Tech Bul "Reducing Electronic RF QRM", & "Stopping HF Tx/Rx SMPSU QRM"
Why don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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