I agree with Barry, as usual. All manner of internal problems can be
masked by the introduction of sufficient external noise . . .
A receiver with antenna disconnected or terminated in the specified
input impedance, usually 50 ohms resistive (at least on paper), should
produce no output other than the antenna-port input noise plus
whatever front-end noise is being generated internally. Additional
artifacts such as birdies, hum and/or undesired reception of external
signals represent deficiencies that should not be present in a
properly designed, implemented and operated receiver.
The first thing I do in evaluating any receiver is to disconnect the
antenna and turn up the audio gain with full r-f gain and listen
critically over the entire frequency range. Anything other than input
termination noise and front-end noise should not be there.
Sure, this is a narrow, critical view of receiver performance. But
apply the same line of thought to your automobile and see how many
deficiencies you would be willing to accept . . . what if the
equivalent of a "birdie" was the blowing of the horn and/or flashing
of the lights every time certain speeds were attained? Silly, yes, but
how long would you put up with that using the excuse that road noise
masks the sound and you can't see the lights anyway?
73/72, George
Amateur Radio W5YR - the Yellow Rose of Texas
In the 57th year and it just keeps getting better!
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
K2 #489 IC-765 #2349 IC-756 PRO #2121 IC-756 PRO2 #3235
----- Original Message -----
From: "Barry N1EU" <n1eu@yahoo.com>
To: <tentec@contesting.com>
Sent: Friday, January 10, 2003 5:48 AM
Subject: [TenTec] I get nervous when . . .
> Tom WB4BQF said "after I read their review on the
> original Omni 6 where the complained about the birdies
> present when they removed the antenna from the
> receiver input, I put very little faith in their so
> called technical reviews!"
>
> Interesting, because my own reaction is that this
> ended up being a very good technical finding on their
> part.
>
> 73,
> Barry N1EU
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