-----Original Message-----
From: amps-admin@contesting.com [mailto:amps-admin@contesting.com]On
Behalf Of w2fca@cs.com
Sent: 02 July 2002 12:38
To: " AMPS"
Subject: RE: [Amps] 4CX250 IMD
"Conrad G0RUZ" <g0ruz@btinternet.com> wrote:
>
>There is exhaustive documentation about the improvement over zener
>stabilisation in 250B's and similar tubes on G3SEK's website, most of the
>research was done by GW4FRX and I'd say (having been ?subjected to both
>flavours on the air with a high IMD sensitive VHF/UHF Rx) the improvements
>for your neighbours are very worthwhile.
>
'Scuse me, but what is a "high IMD sensitive VHF/UHF Rx"? I could see an Rx
sensitive to high signal strength, but if somebody is transmitting at
144.200 and has output products at 144.210 isn't any Rx going to hear it?
Frank
W2FCA
Well Frank I have an eme station and my rx sensitivity requirements are
limited by cosmic and man made noise. This means that my RX was a little
more sensitive than average and more likely to "hear" the higher order
distortion products produced by inadequate screen supplies. I meant high
IP3 of course not high IMD, sorry for the confusion but it was the middle of
the night when I wrote it :-)
I was implying that I hadn't just added preamps to improve sensitivity
without still having good dynamic range.
Any decent Rx will "hear" the IMD products, especially these days as VHF
RX's have dramatically improved phase noise performance due to the adoption
of transverters with high quality HF rigs.
Sorry for the confusion, one word makes such a difference :-)
Conrad G0RUZ
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