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G8MNY > TECH 03.07.26 15:55l 76 Lines 3975 Bytes #5 (0) @ WW
BID : 64022_GB7CIP
Read: GUEST
Subj: Spectrum IF Demo circuit
Path: JH4XSY<N3HYM<K5DAT<VK3AT<VK7AX<GB7CIP
Sent: 260703/0652Z @:GB7CIP.#32.GBR.EURO #:64022 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (New Feb 10)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
Being involved with course ham training with practicals, I have been doing all
the technical demos for the advanced course, this one shows "under", "critical"
and "over" coupling between 2 tuned circuits.
SETUP
ﾚﾄﾄﾄﾄﾄﾄﾄﾄｿ
ﾚﾄﾄﾄﾄﾄﾄｿ ﾚﾄﾄﾄﾄﾄﾄﾄﾄｿ50ohm ｳSPECTRUMｳ ﾚﾄﾄﾄﾄﾄﾄﾄｿ
ｳ RF ｳ ｳ DOUBLE ｳPickup ｳANALYSERｳ ｳ ｳ
ｳ NOISEﾃﾄﾄｴ TUNED ﾃﾄﾄﾄﾄﾄﾄﾄｴADAPTOR ﾃﾄｴ X-Y ｳ
ｳSOURCEｳ ｳXTAL SETｳSingle ｳ0.4-2MHzﾃﾄｴDISPLAYｳ
ﾀﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾙturn ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾄﾄﾙ
I cheated with the use of my RF Noise Bridge as a noise source and my Crystal
Set with its 2 sliding coils on a ferrite rod, as the variable couple tuned
circuits.
Using a noise source instead of a spectrum analyser's tracking generator is not
ideal and the display is quite wobbly, but using a low display video bandwidth
and slow sweep rate (50Hz) helps.
DEMO 1 ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ
Single tuned circuit ｳ _ ｳ
ﾚﾄﾄﾄﾄﾄﾄｿ = = = = = = = = = = = = = = = = ｳ /' '\ ｳ
ｳ RF ﾃﾄ(((()ｿ_ long ferrite rod ﾚ()ﾄﾄTo ｳ / \ ｳ
ｳ NOISEｳ ｳ/| ﾀﾄﾄﾄﾄAnalyser ｳ / \ ｳ
ｳSOURCEｳ === ｳ ./ \. ｳ
ﾀﾄﾄﾂﾄﾄﾄﾙ /ｳ ｳ-ﾄﾄ~ ~ﾄﾄ-ｳ
ﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ
Shows broad tuned circuit
DEMO 2 ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ
Under coupled tuned circuits ｳ _ ｳ
ﾚﾄﾄﾄﾄﾄﾄｿ = = = = = = = = = = = = = = = = ｳ / \ ｳ
ｳ RF ﾃﾄ(((()ｿ_ _ﾚ(((()ｿﾚ()ﾄﾄTo ｳ ﾞ ﾝ ｳ
ｳ NOISEｳ ｳ/| |\ｳ ｳﾀﾄﾄﾄﾄAnalyser ｳ ﾝ ﾞ ｳ
ｳSOURCEｳ === === ｳ ｳ / \ ｳ
ﾀﾄﾄﾂﾄﾄﾄﾙ /ｳ ｳ\ ｳ ｳ _.-~ ~-._ ｳ
ﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ
Narrower & better skirt
DEMO 3 ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ
Over Coupled tuned circuits ｳ _ _ ｳ
ﾚﾄﾄﾄﾄﾄﾄｿ = = = = = = = = = = = = = = = = ｳ / \ / \ ｳ
ｳ RF ﾃﾄ(((()ｿ_(()ｿﾚ()ﾄﾄTo ｳ ﾞ ~-.-~ ﾝ ｳ
ｳ NOISEｳ ｳ/| ｳ/| ｳﾀﾄﾄﾄﾄAnalyser ｳ ﾝ ﾞ ｳ
ｳSOURCEｳ === === ｳ ｳ / \ ｳ
ﾀﾄﾄﾂﾄﾄﾄﾙ /ｳ /ｳ ｳ ｳ.-~ ~-.ｳ
ﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ
Always wide & double hump
DEMO 4 ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ
Critical Coupled tuned circuits ｳ ｳ
ﾚﾄﾄﾄﾄﾄﾄｿ = = = = = = = = = = = = = = = = ｳ /~ﾄﾄ~\ ｳ
ｳ RF ﾃﾄ(((()ｿ_ ﾚ(((()ｿﾚ()ﾄﾄTo ｳ ﾞ ﾝ ｳ
ｳ NOISEｳ ｳ/| ｳ/| ｳﾀﾄﾄﾄﾄAnalyser ｳ ﾝ ﾞ ｳ
ｳSOURCEｳ === === ｳ ｳ / \ ｳ
ﾀﾄﾄﾂﾄﾄﾄﾙ /ｳ /ｳ ｳ ｳ _.-~ ~-._ ｳ
ﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ
Almost ideal square top
See also my TECH buls on "RF Noise Bridge for LF, MF, & HF", "A Quality Crystal
Set" & "Spectrum Analyser mods 88-89".
Why don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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