Search results

The problem of the Elektor SDR is the noisy op amplifier. An low-noise op as the TS464 or TS974 instead the TS914 gives bettler performance.

You Need additional the teensy audio board, which is use as ADC for the analog I/Q signals from the Elektor SDR.

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!

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!

Many thanks for the short description!

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 available at some shops. These chips are good for RF frequencies up to 70MHz and more! I think the RF...

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 reach frequency lower than 3,5MHz.

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 other 2fo setup without a 7474 Johnson ring counter is the direct drive of the 74CBT3253 with 2fo...

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!

For WFM change the sampling capacitors C7, C8, C9, C10 from 270n to 2.7 ... 4.7n to get the necessary baseband BW.

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

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 100MHz. The Performance is the same as with the 4xfo up to 70MHz. But the QRP-Labs receiver module...

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 74LVC4066 or 74ALVC74, a little bit. The switching frequency of the Potato analog switches will be at...

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 or CLK2, which one is simpler on the PCB: Then configure the 5351 so that CLK0 or CLK2 (which...

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 100Mhz. The 74LVC4066 has the same max. switching frequency and a the switches a bandwide of max...