Steve, my experience with the Drake LPF's is that after sustained use at
1.5 KW, they start to fail. Probably capacitor dielectrics are breaking
down or something similar. They are really only rated for 1 KW and they
were manufactured when the legal power was 1 KW input. So they were
probably designed to routinely handle 750W or less.
73, Joe
Steve Thompson wrote:
>----- Original Message -----
>From: Steve Lawrence <smlx@earthlink.net>
>To: <amps@contesting.com>
>Sent: 16 November 2002 07:19
>Subject: [Amps] LP filter effects
>
>
>
>
>>I have an old Drake 1KW LPF in line running 1500w output from an Alpha 87A
>>to a TH7DX. It's worked fine for several years. I've pulled the LPF out of
>>the line. At 28000 with 1500W out, the reflected power dropped from 200 to
>>100 watts. There is also an improvement on 20 and 15.
>>
>>Comments appreciated.
>>
>>
>Assuming the power meter is between the LPF and antenna, it's difficult to
>see how the LPF could be increasing the harmonic level. Another possible
>cause is that your meter has poor directivity and heightened sensitivity to
>harmonics. I'd say that's much more likely.
>
>Steve
>
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