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.
>
>
>
>
>--
>FAQ on WWW: http://www.contesting.com/ampsfaq.html
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>Search: http://www.contesting.com/km9p/search.htm
>
>
--
FAQ on WWW: http://www.contesting.com/ampsfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|