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Type: Posts; User: Karlchen

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    Hi Bill, such wideband transformers are...

    Hi Bill,

    such wideband transformers are available from Coilcraft

    https://www.coilcraft.com/getmedia/a455fe28-d328-4aef-ae99-abd4ca49066a/wb.pdf

    and are also available as free samples!
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    Your calculation is only right for the 3253 with...

    Your calculation is only right for the 3253 with the internal 1:4 decoder. A QSD with a 4066 switch IC each switch of the four switches are a half RF period on and of!
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    Many thanks for the short description!

    Many thanks for the short description!
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    At the Potato online shop you can get some of...

    At the Potato online shop you can get some of there bus-switches

    https://www.ebay.com/str/potatosemi/GHz-Bus-Switch/_i.html?_storecat=19786622

    Where is the problem? The 74LVC4066 is also...
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    You are right, QRP-Labs use the 90 degree direct...

    You are right, QRP-Labs use the 90 degree direct drive of the 74CBT3253 with the QCX tranceiver. The great disadvantage of this is the 3,5MHz low cuttoff frequency. With the 2fo/fo drive you can...
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    If the OMD will be used in the integer mode and...

    If the OMD will be used in the integer mode and the divisor is a power of two, so the duty cycle is 50%. Also you can use the output R diviser with a power of two, that gives a duty cycle of 50%. An...
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    Hi Les, you must change C13 and C15 from 3.3nF...

    Hi Les,

    you must change C13 and C15 from 3.3nF to 47...68pF at the OP amplifier also. They build a LPF in combination with R10 and R11/P1!
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    For WFM change the sampling capacitors C7, C8,...

    For WFM change the sampling capacitors C7, C8, C9, C10 from 270n to 2.7 ... 4.7n to get the necessary baseband BW.
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    Instead of the PCM1808, take a look at the...

    Instead of the PCM1808, take a look at the PCM1804 or PCM4202.

    Regards

    Karlchen
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    I use the 2xfo with a modified QRP-Labs receiver...

    I use the 2xfo with a modified QRP-Labs receiver module and a ugly constructed frontend with the 74ALVC74/74LVC4066. I test this for receiving of the 6m (50MHz)/4m (70MHz) band and FM broadcast at...
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    I'm knowing the Potato chips and the analog...

    I'm knowing the Potato chips and the analog switches don't have switching frequencies of 1GHz and more. The 1GHz and more are the bandwidth of the switches. But, they are somthing better as the...
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    Hi Les, I don't have the Elektor SDR. You have...

    Hi Les,

    I don't have the Elektor SDR. You have four options to work with 2xfo, cut the trace from CLK1 of the 5351 to one clock pin (3 or 11) of the 74AC74 and connect the open clock pin with CLK0...
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    Hi Les, change the 74HC4066 to a better...

    Hi Les,

    change the 74HC4066 to a better 74LVC4066.

    The 350MHz of the 3253 is the max. high-pass frequency of the switches and not the switching frequency. The max. switching frequency is about...
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