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G8MNY > TECH 09.11.25 17:52l 61 Lines 2540 Bytes #4 (0) @ WW
BID : 44606_GB7CIP
Subj: Spectrum Harmonic Demo circuit
Path: JH4XSY<JE7YGF<LU4ECL<VK4OT<VK6ZRT<GB7CIP
Sent: 251109/0844Z @:GB7CIP.#32.GBR.EURO #:44606 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (Updated May 09)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
Being involved with ham training, I have been doing all the technical demos
including AM & FM (Signal Generator) & this one for harmonics....
ﾚﾄﾄﾄﾄﾄﾄﾄﾄｿ
50�ｳSPECTRUMｳ ﾚﾄﾄﾄﾄﾄﾄﾄｿ
Bypass ﾚﾄｴADAPTOR ﾃﾄｴ X-Y ｳ
ﾚﾄﾄﾄﾄﾄﾄｿ ﾚﾄﾄﾄﾄﾄﾄｿ ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ ｳ ｳ0-90MHz ﾃﾄｴDISPLAYｳ
ｳRF SIGｳ ｳDIODE ｳ oﾙ ﾚﾄﾄﾄﾄﾄﾄｿ ｳ ｳ ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾄﾄﾙ
ｳ 6MHz ﾃﾄﾄｴPROBE ﾃﾄﾄoﾄ>oﾄﾄｴ VIDEOｳ ﾀo ｳﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ
ｳ 1V ｳ ｳINSERTｳ ｳ WALL ﾃﾄﾄo<ﾄoﾄﾄﾄﾁｴ SCOPE ｳ
ﾀﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾄﾙ ｳFILTERｳ TｳWAVEFOREMｳ
ﾀﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ
I cheated with the use of a diode probe (series schotky diode for UHF) insert
to produce a poor signal when the sig gen is set to 1V output. This caused the
RF sine wave is bent enough to see the harmonics on 6MHz on a scope (>20MHz) &
the diode output is terminated into 50� by the spectrum analyser.
The filter I had is an 8 section M derrived video LPF & is 40dB down @ 8MHz,
but only 2dB down @ 6MHz. But any suitable filter will show the benefits of a
LPF after a harmonic rich source.
SPECTRUM DISPLAYS
NO FILTER WITH FILTER
dB f1 Rich harmonic spectrum dB f1
0 ｴ ｳ f2 0 ｴ ｳ Cleaner
-10 ｴ ｳ | f4 -10 ｴ ｳ Spectrum
-20 ｴ ｳ ｳ f3 | f6 -20 ｴ ｳ
-30 ｴ ｳ ｳ ｳ ｳ f5 | f7 f8 -30 ｴ ｳ
-40 ｴ ｳ ｳ ｳ ｳ | ｳ . | -40 ｴ ｳ
-50 ｴ ｳ ｳ ｳ ｳ ｳ ｳ ｳ ｳ -50 ｴ ｳ f2
-60 ﾁﾄﾄﾄﾁﾄﾄﾄﾁﾄﾄﾄﾁﾄﾄﾄﾁﾄﾄﾄﾁﾄﾄﾄﾁﾄﾄﾄﾁﾄﾄﾄﾁﾄ>F -60 ﾁﾄﾄﾄﾄﾁﾄﾄﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄ>F
6 12 18 24 30 36 42 48MHz 6 12MHz
SCOPE DISPLAYS
/''\ /''\ /'`\ /'`\
| | | | | | | |
RF _ﾝ ﾞ______ﾝ ﾞ____ ﾝ ﾞ ﾝ ﾞ
ﾞ ﾝ ﾞ ﾝ
| |
Distorted RF With Filter \../
See also my buls on "SSB Demo circuit", "Scope RF Trick", "Tuned Circuit Scope
Demo" & "Oscilloscopes".
Why don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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