Let me give you an example of a poorly designed radio!
From: "John"
To: "'Russ Kiehne'" <[log in to unmask]>
Subject: RE: [Grundig-S-350] Still an awesome radio!!!
Date: Thursday, March 06, 2003 7:11 AM

Russ,

 

Late last night I was sitting in bed tuning around the SW band with the
"Grundsun" (or maybe "Techdig") and found quite a few IF images on the
band that didn't belong there,  I was receiving stations on frequencies
where I knew they weren't..WWV on 9090?  Again on 10910.then I found
this, I guess I am not alone.

 

You didn't see this on E-ham, it's the review right under the glowing
one you sent me..

 

++++++++++++++++++++++

 

This receiver has a tragic flaw that renders it almost useless for a
serious SWL: IF frequency images, causing most signals to appear not
only at carrier frequency, but also +/- 910 kHz of carrier frequency:
obviously the second harmonic of the IF. So, WWV-10000 kHz appears at
about 9090 kHz, 10000 kHz, and 10910 kHz (the lower image the stronger
of the two.) Therefore, the powerful signals in SW bands are repeated
above and below the proper bands, and intermodulate with 'real' signals
there, causing birdies and beats. 

The images are independent of antenna used, and can occur with the built
in whip, or with an external antenna of any length; also they are
independent of RF gain setting. But since they are weaker than the
primary signals, they *may* appear superficially to go away or be
attenuated so that they aren't noticed except with fairly strong signals
(say, S2 or above). 

Unfortunately, with practically ANY setting of the RF gain, and with an
external antenna, they appear with MOST of the SW stations one is trying
to receivee: so you have to watch the frequency display and KNOW the
proper carrier frequency to be sure you are not tuned in to an image.
Otherwise your station will be abnormally weak, noisy, and whistly.

It is incredibly frustrating, say, to find that powerful HAM signals in
SSB from the 40M band, will mix in and/or cover up SW stations in the
49M international SW band. And the images cause such debilitating
birdies that they make the band seem noisy and crowded with hetrodynes.

Other flaws of the radio are erratic tuning and drifting of the local
oscillator: drift appears to be about 1 kHz every two or three minutes,
so one is forced to retune fairly often to listen to a program. The
tuning mechanism is fully analogue, with a standard variable capacitor,
pulleys, and dial cord; a planetary gear is affixed on the front of the
radio, and has slop and backlash. This causes "centering" of the
station, even at low frequencies on the MW band, to be difficult. And
the image problem even occurs in that band, too: strong signals leaking
from the IF oscillator will appear over 'real' carriers.

If the image problelem is fixed, the receiver would be a very usable one
(even allowing for the imperfect tuning.) I don't recommend buying this
radio at present: be sure to keep up with product reviews, and make
certain your dealer is willing to let you return the unit if it is not
working properly: I tried three and found them all about the same though
the volume of the images varied from radio to radio, one being FAR worse
than the other two (and it had much higher RF gain and senstivity too.)
I decided that this radio is "not ready for prime time" and will pay for
a more expensive model. 

My previous receiver experience dates back to 1954 when I started
listening to SW, and includes many portables from Zenith to Sony and
Grundig; Hammarlund and Icom tabletop "pro" SW receivers, and general
purpose AM/SW sets from Magnavox, Nordmende, Radio Shack, Knight,
Heathkit, and other companies. My impression of the Grundig S350 is that
it would be a fantastic radio IF the RF design and filtering did not
have this fatal flaw at present. One hopes that Tecsun/Eton/Grundig will
correct the problems as soon as possible to make this a competitive and
satisfactory unit.

 

++++++++++++++++++++

 

The sample I have exhibits the same intermod products as described as
well.  That's the stuff China, keep pumping out the crap..

This is what I would have expected!  Save your $$$, hey, want to buy
mine?

John.