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>Från: "sm5ki" <sm5ki@algonet.se>
>Till: G0MJW <mike@g0mjw.freeserve.co.uk> , amps@contesting.com
>Ämne: SV: [AMPS] IMDs
>Datum: mån 6 mar 2000 20.11
>
>On what band?
>----------
>>Från: "G0MJW" <mike@g0mjw.freeserve.co.uk>
>>Till: <amps@contesting.com>
>>Ämne: [AMPS] IMDs
>>Datum: mån 6 mar 2000 12.14
>>
>
>>
>>I happened to have an FT690R on the bench and the posts regarding IMDs
>>prompted me to look at the results from a "typical" solid state driver. The
>>FT690R is not renound for its quality output but I expect many older solid
>>state rigs are similar. The test involved a 2-tone test at 1.2 kHz and
>>2.2kHz, with adjustments made to make both tones equal in level. The values
>>in the tables are levels of IMDs relative to one of the tones. They are 6dB
>>better relative to PEP. The ALC was used to set the output.
>>
>>Here are some results.
>>
>>12.5V supply.
>>
>>Power 3rd 5th 7th 9th 11th 13th 15th 17th
>>2.5W -28 -29 -41 -47 -49 -53 -62
>>3.0W -24 -30 -37 -48 -53 -53 -57 -64
>>4.0W -16 -30 -35 -37 -43 -53 -58 -61
>>
>>At 5W I only measured the 3rd order, as it was only -13dB !
>>
>>13.8V Supply
>>Power 3rd 5th 7th 9th 11th 13th 15th 17th
>>2.5W -30 -32 -41 -47 -51 -57 -64 -68
>>
>>10.1V Supply (I.e. NIMH battery)
>>Power 3rd 5th 7th 9th 11th 13th 15th 17th 19th
>>2.5W -18 -29 -31 -40 -51 -53 -54 -55 -59
>>
>>
>>The results show two things.
>>
>>1. It is only sensible to extract 2.5W from the FT690. 2.5W set on FM
>>measures an average power of 1.5W under 2 tone testing, that is 3W PEP.
>>Under these conditions, the rig is really not all that bad and could be used
>>to drive a good quality linear amplifier without offending the locals too
>>much.
>>
>>2. When running of the internal battery, the IMDs are poor. This is OK as
>>long as there is no big amplifier following the rig but is a strong warning
>>for those intending to go out portable with a car battery and a small linear
>>as the signal will be awful once the battery starts to go flat.
>>
>>
>>
>>
>>--
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>>
>>
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