Topband: Collins R390 and 75A4 on 160m

[Michael Tope]

When I enquired about the 75A4 some time ago, several
people replied that despite its reputation, it has very poor
dynamic range (see the following message). I don't know
about the R390.

73 de Mike, W4EF......................

[snip]

----- Original Message -----
From: "James D. Jorgensen (by way of Bill Tippett <btippett@alum.mit.edu>)"
<jandrjor@interaccess.com>
To: <topband@contesting.com>
Sent: Friday, August 17, 2001 7:01 AM
Subject: Re: Topband: Collins 75A4


> The following data for the Collins 75A-4 were presented in a talk at the
1979
> W9DXCC Meeting and are attributed to Bob Sherwood.
>
> Measurements done at 500 hz bandwidth.
>
> Noise floor:  -143.5 dBm
> Intermodulation:
> @20 Khz
> dynamic range: 66 dB
> 3rd order intercept:  -44.5 dBm
>
> @2 Khz
> Dynamic range:  tone
> 3rd order intercept:  -- (I think this means it couldn't be measured)
>
> Blocking dynamic range:
> @ 20 Khz:  95 dB
> @ 2 Khz:  tone
>
> Sideband noise:
> Level below the noise floor:
> @ 20 Khz:  blocking
> @ 2 Khz:  tone
>
> AGC range:
> 0 to -100 dBm, input dB:  1.5
>
> As you can see, the intermod and blocking characteristics are not very
good,
> especially at close spacing.
>
> Best wishes,
> Jim, K9RJ
>
>
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