Digikey was a strike out with 1 filter for 86 cents but order was 1000 units. Mouser however has a wide assortment very reasonable and by the single units. Hardest thing will be soldering them. Regards Paul WB8TSL
On Tue, Dec 1, 2015 at 8:29 PM, paul swed <[email protected]> wrote: > Hello to the group have indeed done the 1575 down to 35.42 to 75.42 and > upconverter trick. > Thats what I used for 2-3 years now and thought it was time to move beyond > that approach. Especially due to the earlier conversation on old receivers > and that they should still work just fine if you do not care about the date. > > I actually have 2 versions of the 35 to 75 converter. One using an odetics > down converter and another using a starlink gps receiver. Both have 35.42 > MHz IFs. Old stuff you can get a soldering iron into. > > No intention to put this on the tower and mini-circuits makes a good BPF > for the 75 MHz IF. Since I will believe the actual antenna has a 1571 > filter in it I was thinking of skipping it down in the shack. > > Will see what digikey and mouser has in the way of filters and if > inexpensive may buy one. I keep thinking I may actually have one also. > Thanks again everyone. > Paul > WB8TSL > > On Tue, Dec 1, 2015 at 7:53 PM, Alex Pummer <[email protected]> wrote: > >> for 70MHz it does not hurt to match the cable to the filter at the >> antenna unit [down converter] end and also match the filter at the >> receiver upconverter end, the cable will pick up enough noise to overdrive >> the 70 something receiver's input [ the "outside" field will drive a >> current in the cable's shield, but not in the center conductor, that >> current causes noise voltage between the two end of the cable's shield >> which will end up at the input of the receiver, therefore it need to be >> filtered out before it hits the mixer......also the down converter's LO's >> reference is sensitive to the noise which the cable will pick up [ will >> cause phase noise ], therefore it needs to be filtered ..... >> That down up converter system is an interesting project but it is not >> that simple as it looks >> 73 >> KJ6UHN >> Alex >> >> >> On 12/1/2015 2:57 PM, Bob Camp wrote: >> >>> Hi >>> >>> Here’s sort of a backwards look at it: >>> >>> Do you *need* an IF filter in the downconverter? By that I’m asking >>> about a >>> filter better than a simple LC tank. Did they put the filter in the >>> downconverter >>> or in the main box? I would think that putting a fancy filter up by the >>> antenna >>> would have been a less likely thing to do than putting it down in the >>> main box. >>> >>> Bob >>> >>> >>> On Dec 1, 2015, at 9:48 AM, paul swed <[email protected]> wrote: >>>> >>>> Thanks everyone. The Meinberg is nice and maybe available from Ebay by >>>> Alex's link. But its 35.42 much as the Odetics down converter. I am >>>> looking >>>> to create a 75.42 Mhz IF. >>>> Mini-circuits makes just the right parts. But had several IF bandwidths >>>> available. >>>> So will go with the 2 or so MHz filter as suggested. >>>> >>>> I have the typical GPS better quality high gain antenna 1/2" Heliax >>>> feed to >>>> a low noise gain block that makes up for the loss of a 8 X splitter. >>>> I may add a 1575 filter ahead of the 10 db amplifier and then hit the >>>> mixer. I think I have a filter. I actually question that I need the >>>> filter >>>> or 10 db amp. May build without it to see what happens. Can easily add >>>> it. >>>> The LO will be a mini-circuits dsn-2036 followed by a 10 db amp to drive >>>> the mixer another mini-circuit DBM. The IF drives a bpf-a76+ and then >>>> will >>>> follow that with 30 db of gain at 75 MHz. >>>> At least thats my thinking. >>>> Regards >>>> Paul >>>> WB8TSL >>>> >>>> On Tue, Dec 1, 2015 at 1:36 AM, Magnus Danielson < >>>> [email protected] >>>> >>>>> wrote: >>>>> Hi, >>>>> >>>>> This is a side-track to Pauls original question, but maybe a nice >>>>> little >>>>> point to make now that Peter touched on the subject. >>>>> >>>>> To elaborate a little on C/A and multipath surpression. >>>>> The multipath surpression of the receiver depends on code rate, >>>>> bandwidth >>>>> and correlator spacing. P-code is able to surpress more, and the C/A >>>>> code >>>>> errors look about the same as the P-code, but scaled accordingly. >>>>> Increasing the bandwidth helps to reduce the C/A errors, but taking the >>>>> next step of using narrow correlators further reduces the error. This >>>>> is >>>>> shown already in the classical Spiliker book, but further readings from >>>>> Novatel could be nice. >>>>> >>>>> Increasing the bandwidth and narrowing the early and late correlator >>>>> taps >>>>> both have the effect of reducing the time over which energy goes into >>>>> the >>>>> E-L difference, and hence reducing the impact of multipath into the >>>>> solution. >>>>> >>>>> Cheers, >>>>> Magnus >>>>> >>>>> >>>>> On 12/01/2015 06:00 AM, Peter Monta wrote: >>>>> >>>>> What should the IF pass band bandwidth be? >>>>>>> >>>>>>> >>>>>>> For GPS C/A with wide correlator, about 2 MHz; if you want Galileo >>>>>> BOC and >>>>>> (eventually) GPS L1C, or legacy C/A with narrow correlator, about 8 >>>>>> MHz; >>>>>> for GPS P code about 20 MHz. Books on GNSS software receivers will >>>>>> detail >>>>>> the many tradeoffs available---if you're starting out with a >>>>>> proof-of-concept lab receiver, go for 8 MHz. >>>>>> >>>>>> Cheers, >>>>>> Peter >>>>>> _______________________________________________ >>>>>> time-nuts mailing list -- [email protected] >>>>>> To unsubscribe, go to >>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>>> and follow the instructions there. >>>>>> >>>>>> _______________________________________________ >>>>>> >>>>> time-nuts mailing list -- [email protected] >>>>> To unsubscribe, go to >>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>> and follow the instructions there. >>>>> >>>>> _______________________________________________ >>>> time-nuts mailing list -- [email protected] >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>> >>> ----- >>> No virus found in this message. >>> Checked by AVG - www.avg.com >>> Version: 2016.0.7227 / Virus Database: 4477/11098 - Release Date: >>> 12/01/15 >>> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
