[1000mp] MP Roofing Filter from INRAD -- hiss reduction needed?
Uwe Egen
Uwe.Egen at t-online.de
Thu May 20 05:40:00 EDT 2004
Hi Dale,
Suppose some problems sitting "between operators ears" but I confirm
the results from you switching in/out the EDSP of my Mk V.
Big hiss reduction - no. Small reduction - yes.
I tried about 20 times to hear small signals better, EDSP rx "on/off".
Let me say this. I never got better readings incl. Heil Headset/SP-8.
Sure to hear lowering 300 Hz to 100 Hz heavy but only in that case
when the received signal generates below 300 Hz.
Suppose your ears are OK - hi hi.
I wonder about hams who took a small change in components and find
great difference.
Design todays transceiver it's very complex system requires thousends
of EE development hours. Stage level calculations, simulations, component
selections etc.
Sure I can't say every design is the best what we get for the bucks.
Small changings may be OK but success reports sound often like wishfull
thinkings. Hams are some times very enthusiastic. Perhaps a new rig is
the best of all or part of the hell.
Long time ago I made several replacements I read in ham magazines
for Drake-4 or -7 lines. Description, after change you will get great
effect. Let me say the word "disappointment" almost.
Real success needs strong and carefully changings to avoid strange
behavior under all circumstances.
I suppose putting in the roofing filter will be great. Still waiting.
73 to all 1000's,
Uwe, DL9NC
"D. J." <dalej2 at mac.com> schrieb:
> Hi Mike,
>
> Well, thankyou for the tips and about 7-7. I just tried turning off
> 7-7, (off to 100-3100 Rx) I cannot for the life of me tell a
> difference, must be my ears? I did put my sound level meter on it and
> it also showed no difference. So I am stumped, no kidding. My radio
> was built in Feb 04 could it have some updates no one knows about? I
> will keep checking and watching the postings for more information. Yes
> that roofing filter idea of Georges is the best idea I've seen yet for
> improving these receivers. I had a Mil-Spec 1030 some time ago which
> had a 8 khz roofing filter, and Collins 250 hz filte in the 455 IFr,
> it was a kool machine.
>
> I don't think you need to change those diodes. I looked up the ones
> for switching rx bandpass filters and they are pins already. I think
> when you change pin diodes the biasing may have to be changed also
> depending on the diode, maybe only one resistor. Will you go to the
> HP's? I bought a bunch one time from Newark. Mouser most likely has
> them too. I think they were -3080s, but not for sure.
>
> 73
> Dale, K9VUJ
>
>
> On May 18, 2004, at 12:54, Mike Schatzberg wrote:
>
> > Hello Dale:
> >
> > If you want to check the difference between the digital product
> > detector,
> > and the analog detector in the Mark V, it can be turned on and off in
> > menu
> > 7-7. If you select off, you will be using the analog detector. I
> > like to
> > use the 100-3100 setting, with the digital detector on SSB. This
> > works very
> > well for weak stations, and seems to improve the signal to noise ratio.
> >
> > If the band conditions permit, and you want to improve the signal to
> > noise
> > ratio further, I like to use menu 5-0, and set it to the 8.2-455
> > position,
> > to remove the filter from the 2nd IF, and use only the 6.0 filter in
> > the 3rd
> > IF. If you do the comparison between the two detectors as above, with
> > the
> > normal filter selection button lit, you will see a rather dramatic
> > difference. I like to use this set up generally, as it also produces
> > the
> > best fidelity with stronger SSB stations. If the QRM becomes a
> > problem, you
> > can either push the IDBT button, and superimpose the digital filters
> > over
> > the analog positions, or push the NAR1 filter selection, and have the
> > 2.4
> > khz filters cascaded in place the single 3rd IF filter.
> >
> > I also have noted that the best signal to noise ratio seems to come
> > with
> > about a negative 0.180 setting in menu 8-9, r-usbcar. This also seems
> > to
> > improve the noise floor noticeably.
> >
> > Regardless, later this summer, following some other projects, and
> > despite
> > some criticism that it may not work well, I intend to change all the
> > switching diodes in both the preamps and front end. I will finally
> > find out
> > what PIN diodes do, or don't do for the Mark V.
> >
> > As long as the new roofing filter is switchable, it certainly looks
> > like it
> > is a worthwhile change if you suffer from intermod issues. Even out
> > here in
> > the country I have one or two signals I would like to see removed,
> > probably
> > from strong broadcast station mixes. I also intend to enable the
> > antenna
> > tuner to work during receive when desired, to improve the Q of the
> > front
> > end. I wonder what the reason is that Yaesu doesn't offer that
> > option, I
> > want to give it a try.
> >
> > Regards,
> >
> > Mike Schatzberg
> > WB2AJI
> > ----- Original Message -----
> > From: "D. J." <dalej2 at mac.com>
> > To: "All Things Pertaining To The 1000mp Series"
> > <1000mp at mailman.qth.net>
> > Sent: Tuesday, May 18, 2004 1:14 PM
> > Subject: Re: [1000mp] MP Roofing Filter from INRAD -- hiss reduction
> > needed?
> >
> >
> >> I just tried turning of the EDSP in menu 0-9 and I could tell no
> >> difference in receiver noise, the tone changed slightly but the output
> >> from the speaker did not, I had a sound level meter on the speaker.
> >> The antenna input was on a dummy load. Am I doing it right?
> >>
> >> Also, could you provide details about disconnecting the manual notch,
> >> where did you do it?
> >>
> >> tnx
> >> Dale, K9VUJ
> >>
> >> On May 18, 2004, at 9:31, Harry Yingst wrote:
> >>
> >>> if you turn off the DSP in the Menus you should hear the hiss quite
> >>> well
> >>>
> >>>
> >>>
> >>>
> >>> --- Pete Smith <n4zr at contesting.com> wrote:
> >>>> At 10:25 AM 5/18/2004, you wrote:
> >>>>> Harry Yingst <ab2pn at yahoo.com>
> >>>>
> >>>>
> >>>> Sorry, Harry, I don't understand -- turning *what* off?
> >>>>
> >>>>
> >>>> 73, Pete N4ZR
> >>>> The World HF Contest Station Database
> >>>> was updated on April 26, 2004
> >>>> 2706 contest stations at
> >>>> www.pvrc.org/WCSD/WCSDsearch.htm
> >>>>
> >>>> _______________________________________________
> >>>> 1000mp mailing list
> >>>> 1000mp at mailman.qth.net
> >>>> http://mailman.qth.net/mailman/listinfo/1000mp
> >>>
> >>>
> >>> =====
> >>> Harry - AB2PN
> >>>
> >>> -
> >>>
> >>>
> >>>
> >>>
> >>> __________________________________
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