1-01-15 22.44, skrev Tom Rauch på w8ji@contesting.com följande:
>
> Here are some specs:
>
>
> But back to Tom's point. I went through a
> number of swept test data and
> was
> surprised to find that my generalization was not
> true in all cases. Here
> is
> the 5-kHz data for the rigs I checked:
>
> (In alphabetical order...)
>
> Rig BDR IMD DR
> Elecraft K2 126 88
> ICOM IC-706 MkII G 86 74
> ICOM IC-756 98 67
> ICOM IC-756 Pro 104 80
> ICOM IC-775DSP 104 77
> Kenwood TS-570D 87 72
> Ten-Tec Omni 6+ 119 86
> Yaesu FT-1000MP 111 83
> Yaesu FT-1000MP Mark V 106 78
> In the vast majority of cases, the numbers are
> less than at the 20 kHz
> spacing, but the amount of variation between
> similarly priced radios was
> unexpected.
>
> Note that some of the above rigs would
> experience a _blocking_ response
> from
> an S9+30 signal that was more than 5 kHz away.
>
> end of repost......
>
>
> OK, if you look at the above, you will see most
> rigs aren't so good at close spacing. THe
> Kenwood 570 blocks about the same as a IC-706.
>
> My modified Drake R4C's block at anywhere from
> zero to plus ten dBm at 1 kHZ spacing!
>
>
>
>
>
>
>
>
>
> 73, Tom W8JI
> w8ji@contesting.com
>
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>
>
" What is wrong with present days receivers" from 1956 QST stated you have
to have your selectivity as close to the antenna as possible to get rid of
strong qrming sigs as soon as possible. This statement is still true
nowadays but forgotten in the most modern rigs with the selectivity at the
end of the if chain. Let us see how the new TS 2000 performs? It has no
extra filters to buy.
In your old DRAKE receiver, insert one of the USB/LSB-filters from one the
DRAKE-line transmitters after the first rx mixer and watch the improvement.
I do not know whats inside the filter but if you are lucky it is a ladder
filter with no ferrite transformers that degrade the filters big signal
performance. Sherwood filters are of course OK but is this firm still in
business? KVG filters were measured in the VHF COMMUNICATIONS years ago.
The first roofing filter must be so wide so you can run FM. But are there
any narrower filters at these high frequencies?
de Hans SM5KI
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