Thanks for the information on the Ten Tec Eagle noise blanker. Right now I
have a Kenwood TS950SD which has a pretty good noise blanker in it, in
terms of it taking out much of the RFI crud I get, but it also has a
tendency to distort the audio and does produce some IMD products under
heavy band conditions. It is kind of a trade off between the noise (which
is intermittent) vs what the NB produces. Even when this intermittent,
irritating noise isn't present, the NB will reduce the background noise
some, which is nice.
I did see one video of the Eagle's NB in action which made a station hidden
beneath the noise suddenly copiable, and it didn't seem to produce too must
distortion. I need to check out some more videos on that. The Eagle does
look like a nice rig for the price.
Also, does the internal antenna tuner in the Eagle work on both transmit
and receive, or only on transmit?
73 John AF5CC
On Tue, Nov 14, 2017 at 3:52 PM, <Rick@dj0ip.de> wrote:
> John,
>
> The Eagle's NB is indeed an analog one, and yes, it does distort the
> radio's
> audio signal; ALL NB (by design) must do that.
> They reduce noise by cutting out part of the frequency spectrum, which
> ultimately distorts the audio.
>
> I won't make any kind of claim that analog NBs are better than DSP NBs,
> because I'm sure that is just a question of the combination of DSP chip(s)
> and the firmware. However the Eagle's Analog NBs better than most modern
> radios using DSP NBs.
>
> It is always bad to generalize because there are many differences or
> exceptions, but I will do it below:
>
> The reason the NB often lowers the dynamic range is simple.
> On radios with a high dynamic range, the signal usually go straight into a
> narrow 1st IF filter.
> However it is difficult/impossible to limit pulse noise with a narrow
> filter
> in front of it.
> So they have a wider filter in the NB and thus strong signals can overdrive
> the circuitry within.
>
> The reason the OM5/6/6+ had the broad simple xtal filter in its front end
> was to enable use of a NB.
> The INRAD replacement filter for this improved dynamic range significantly,
> at the cost of the NB. The NB is no longer effective when the INRAD
> roofing
> filter is in place.
>
> Normally we would only use the NB in a mobile environment, where we have a
> small antenna anyway, so this does not create a problem.
> However now days with all the noise we have in our homes, people are
> turning
> on the NB when using larger antennas and then it can be a problem.
>
> As I said, it's hard to generalize.
> Rob Sherwood always scrutinizes the NB carefully in his tests.
> If you really want to know, you should read his individual tests, don't
> just
> look at the table of RX performance.
>
> You will find most of his reviews/tests in full length on my web site,
> here:
> http://www.dj0ip.de/sherwood-forest/sherwood-xcvr-tests/
>
> 73
> Rick, DJ0IP
>
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of John
> Geiger
> Sent: 14 November 2017 20:01
> To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
> Subject: [TenTec] Ten Tec Eagle noise blanker
>
> From the Ten Tec Manual, it appears that the noise blanker for the Eagle is
> not a DSP one, but an analog, hardware one, is that correct?
>
> I have seen a couple of You tube videos which show that the NB is very good
> at taking out RFI noise, but does the NB distort the received signal, or
> lower the receiver's dynamic range like many noise blankers do?
>
> 73 John AF5CC
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