Do you still have an OM5 or 6 to see how its NB works?
Mine never helped with noise like that.
I used the original ANC-4 and a very old "QRM Eliminator" from SEM.
They helped quite a bit.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Carl
Moreschi
Sent: Monday, December 15, 2014 8:01 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] NB verses NR
I am in the country and I have intermittent power line noise. When it is
bad, the Noise Blanker in my Flex 6500 will remove it completely, dropping
the S meter reading by sometimes as much as 10 DB. Very impressive.
Carl Moreschi N4PY
58 Hogwood Rd
Louisburg, NC 27549
www.n4py.com
On 12/15/2014 1:53 PM, Rick - DJ0IP / NJ0IP wrote:
> Peter,
>
> It is as Carl said, if you have a narrow filter before the NB tap, it
> simply won't work.
> In the country, you probably won't need it anyway unless you have an
> electric fence nearby.
>
> I can't recall the filter plan on the original OM6.
> If you series two filters on separate IF frequencies, you get at least
> 10dB more ultimate attenuation than if you series them on the same IF
frequency.
> Don't ask me why, I've long sense forgotten. This was explained by
> DL1BU in about 1979 in a CQDL test of the old Icom 730. I "think" I
> still have that article saved somewhere. Not sure if I could find it
again.
>
> The problem with placing two filters directly in series is, you will
> drop about 6dB of gain, assuming they are narrow filters. This needs
> to be compensated for with a low gain, low distortion amp. I also
> used two 9 MHz filters in series with my old Argonaut 509; I replaced
> the original 4-pole xtal filter with an 8-pole KVG XF-9B, then placed
> a 6-pole 500 Hz Yaesu filter behind it. The signals I could no longer
> hear due to the additional insertion loss were too weak to work anyway
with only 5w.
>
> Ten-Tec was already managing stage-gain better than the JA OEMs when
> they developed the OM5.
> In fact it goes back all the way to the original Omni where they had
> different gain depending on the band.
> However they improved it even more when developing the OM7.
>
> At the end of the day, if it is working for you and you are happy with
> it, then it was a good move.
> That's how I judged my dual-filter in the Argonaut, even though I knew
> it was technically no exactly kosher to do it that way.
>
> 73 - Rick, DJ0IP
> (Nr. Frankfurt am Main)
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Peter
> Bertini
> Sent: Monday, December 15, 2014 6:13 PM
> To: tentec@contesting.com
> Subject: Re: [TenTec] NB verses NR
>
> Rick
>
> I have two of the roofing filters kits from Inrad; they are connected
> in series... since I have the basic Omni VI, I only have one NARROW
> filter selection on the front panel... so I have one of the roofing
> filters always in line. Narrow drops the SSB roofing filter, and
> selects the board with the CW filter. It is in series with the input
> to the monolithic roofing filter on the 9 MHz IF board. My
> understanding is that the NB sampling is after this filter, but I could be
mistaken.
>
> Fortunately, being in a rural area I don't have much need for noise
> blankers. I've often wondered if just buying better quality IF
> filters from Inrad would reduce the need to cascade additional filters
> at 9 MHz to improve the skirt selectivity.
>
> Peter
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