SV: SV: [AMPS] Mission Impossible

[sm5ki]

----------
>Från: "sm5ki" <sm5ki@algonet.se>
>Till: Peter Sundberg <sm2cew@telia.com> , measures <2@vc.net>
>Kopia: amps@contesting.com
>Ämne: SV: [AMPS] Mission Impossible
>Datum: mån 6 mar 2000 19.31
>

>Hej Peter:
>
>In the TS950 two-tone test in QST 1/1991 distorsion is abt 42 dB below pep
>for 3rd order mods. Higher order mods are also very low. This was worst case
>measurment and on most bands it should be even better. However, I cant see
>how much ALC was used in this test? Maybe no ALC? This rig usually sounds
>very clean.
>
>I think the problem is behind the microphone as 150 watts pep is avaiable
>and there is a possibility that too much drive was used for the finals. One
>has also to know how the ALC from the amp was connected and used etc. Did
>they use clipping and did they know how to use it properly? Maybe talked to
>close to the microphone which in some differential pressure electret
>microphones leads to distorsion. Do you remember when the ICOM SM2 first
>came out? Boerge who worked for Bruel/Kjaer quickly found out, you could not
>talk close to that microphone without getting very bad speech quality. This
>has of course nothing to do with splatter outside the passband.
>
>Hej daa de Hans
>
>
>----------
>>FrÂn: Peter Sundberg <sm2cew@telia.com>
>>Till: measures <2@vc.net>
>>Kopia: amps@contesting.com
>>Ÿmne: RE: [AMPS] Mission Impossible
>>Datum: mÂn 6 mar 2000 17.13
>>
>
>>
>>At 07:55 2000-03-06 -0700, Rich wrote:
>>>>Checking the web pages out shows these stations run FT1000MP's, FT1000D's,
>>>>TS-950's, Alpha's, Henry's, you name it.
>>>>
>>>Peter -  'This has got to be an amplifier adjustment problem.  The radios
>>>you mentioned are fairly clean.
>>>
>>>cheers.
>>
>>This is what puzzles me, but there is no doubt that "fine" radios can turn
>>into mean machines if they are improperly adjusted. Many of the signals
>>heard over the weekend had the sound to them that you get from setting the
>>bias too low. I suppose this could be in either the exciter or the
>>amplifier but it must be the easiest thing to check for most amateurs. Then
>>again, one would have to find out what the ZSAC should be..
>>
>>I have been making some test with a good friend of mine re the behaviour of
>>the FT1000D when driven beyond the ALC top level. IMD products 3.5 kc away
>>from from the ssb carrier frequency rises about 10 db just by letting the
>>ALC needle swing a little higher than recommended. This test turned out
>>equal on two FT1000D's, driving different types of amplifiers. There is no
>>doubt that even the FT1000D needs full attention not to sound bad.
>>
>>Listening to the microphone freaks on 14178.00000 in the mornings will tell
>>you that the TS950SDX will splatter, check "Your Friend's" signal out and
>>you will hear quite a lot of hash down the band. And they think they have
>>the best audio achievable on SSB. Well they might (if you like the sound
>>and want to spend 10.000 USD on a mixer/microphone), but out of the
>>passband there is trash. Trash that their friends who want to operate close
>>to the frequency will have to listen for NO reason.
>>
>>So Rich, it could be the amps, it could be the transmitter, but I'd go as
>>far as to say it is the transmitter that makes the signal sound bad in most
>>cases. (Or should we say the combination, to be politically correct..)
>>
>>Ciao,
>>
>>Peter/SM2CEW
>>
>>
>>
>>
>>
>>
>>
>>
>>--
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>>
>>

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