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G0FTD > FT817 28.04.07 09:43l 36 Lines 1262 Bytes #999 (0) @ WW
BID : 080321117PZT
Read: GUEST DL1RX VE7HFY DG4IAK
Subj: Re: Max current from mic 5v pi
Path: DB0FHN<DB0FOR<DB0SIF<DB0ROF<DB0ACH<DB0ACC<DB0GOS<DB0RES<ON0AR<GB7SYP<
GB7PZT
Sent: 070428/0634Z @:GB7PZT.#24.GBR.EU [Kidderminster] #:32108 XSERV410h
Date: Sat, 28 Apr 2007 07:34:11 +0000
From: g0ftd@gb7pzt.#24.gbr.eu (Andy)
To: ft817@ww
Subject: Re: Max current from mic 5v pi
> ZL1ANM wrote:-
>> Also, you're aware that modern rigs generate AM in a low level
>> stage and linearly amplify it, the result being audio that lacks
>> the punch produced by high-level modulation?
Somehow I don't think BBC WS , VOA et al are all using 500KW modulators
to get punch - do you ;-) ?
'HUD:-
> Neil, I think I might be being stupid here (so no suprises there) but can
> you explain why low-level and high-level modulation would sound different?
I agree with HUD. All things being equal the output waveform should be the
same. The "high level" tx combo's sounded "punchy", but all that meant was
it had plenty of distortion in reality.
The "punch" came from all that harmonic distortion and emphasised freq
response from mismatched mic inserts in reality.
These days broadcasters (cue M0PZT) use Optimod units to introduce *selected*
harmonic distortions to create a modulation "reinforcement" effect.
You get AM and FM versions to create the correct "timbre" - which is really
what the subtle distortions are nostalgically referred to.
These days we call them intermod products ;-))
- Andy -
G0FTD @ GB7PZT
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