2.4 GHz bandpass

  • That depends on the amplifier response but I doubt it will be clean. If it is that's clearly good but a mixer that has no image or carrier leakthrough is a rare thing indeed. Also its advisable to check all spurious, not just ones less than 180MHz away. You might get away with a saw filter to clean things up.

  • We know all that IF=28 MHz isn't a good choice. DX-Patrol gives the option but writes a filter is needed then (or you should...).

    52 MHz (50...54) will be a little bit better.


    I use 432MHz, but I asked for someone else who has no 2m or 70cm transmitter.


    Achim, I know that kind of filter. May be from UHF Unterlage (DJ9HO et al...). But if you don't have the tools in your own workshop at home...


    Thanks so far.

  • DL1GNM


    Hello Mike,


    I use 50 MHz as IF for a BU500 up-converter and I ordered a filter from ID-Elektronik. It was adjusted particularely to attenuate the LO frequency of 2350 MHz and it does an incredible job to do that: the attenuation is 92 dB (!), while the pass-through attenuation is indeed very low. I am sure the filter could also be ordered for an IF of 28 MHz,



    Vy 73


    Holger 'Geri', DK8KW

  • That depends on the amplifier response but I doubt it will be clean. If it is that's clearly good but a mixer that has no image or carrier leakthrough is a rare thing indeed. Also its advisable to check all spurious, not just ones less than 180MHz away. You might get away with a saw filter to clean things upI

    I think is other way to get clean signal w/o any filtering stages. i can use in gate-filter, but is not necessary in my case.

    i use AppCAD from HP for a long period, from 1997, is never makes mistakes.

    Righ now i'm build one like this,but total transverter for other HF range. it's for RX and TX simultaneously. can't send circuits and PCB gerber's now, in the future i will do it.

    please see attachments. BOTH STAGES are UP-CONVERTER. now let's do some calculation: 740 x 3 = 2220; 2400 - 2220 = 180. In any case mixer reproduce products in both directions. Any questions?

    about spurs - no closer one than 180 MHZ . see what's amateurs use of for feed and amplifiers stages. feed is not so simple to adjust. amplification power stages have very narrow band with. efficiency of +/-150 MHz not so high.

  • Hello Geri! is not exact brave or not, but BU500 is only mixer with separated stages. i'm familiar with this product, and read page 4. example of 50 MHz is given. also, you can trylowest frequency, but conversion rate and gain will drop. 100 MHz is promissed condition. some amateur was try to use LNB in direct conversion, also same result up to dead point of receiving.

  • Well, Leonid,


    I hear what you are saying. The only thing I can add is that I have been using the 50 MHz IF without problems since last year very successfully, at home as well as portable. I have not measured any considerable drop in performance nor did I have any problem with my signal. it looks clean.


    However, I recommend to use a very steep filter as the ID-Elektronik filter mentioned earlier.


    I have, however, not yet tried any lower frequency, but I am confident that Ewald, DK2DB (= ID-Elektronik) can configure his interdigital filter so that the 28 MHz input of the DX-patrol does not leave any unwanted signals after the filter.



    Best 73


    Holger 'Geri', DK8KW

  • Thank you so far. It's interesting, what is available. The taiyo yuden filter for example. Currently this is not available (mouser, digikey).

    Small, affordable and a quite good attenuation.


    Meanwhile we discussed the AMSAT up converter in combination with a 28-432 MHz transverter.


    But keep on posting interesting solutions.


    73 Mike