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Recent content by Synaps3

  1. S

    Frequency divider on FM transmitter

    I want the deviation to stay the same. I just want the carrier frequency in half. It is an FM transmitter chip, but I want to use it at 50mhz. Will it distort the audio?
  2. S

    Frequency divider on FM transmitter

    I have an FM transmitter with integrated PLL and VCO synth. I want to use the transmitter on a lower frequency. Is there any easy way to divide the signal by 2? I have another chip that has a built in divider that outputs a square wave. If i use the divider function of this chip and modulate...
  3. S

    What info is needed to designate location for PCB assembly process?

    So there are some other questions similar to this, but none of them talk about how to designate the placement of components for the manufacturer. I use a pretty uncommon piece of software for designing my PCBs (sprint layout), so I can't just send the project file because they won't be able to...
  4. S

    Help with loop filter for FM transmitter

    Not sure if that is the case with this particular device because it does have multiple tuning voltage steps/segments throughout the band and I think it was a design to keep it more linear. Anyway, can anyone comment on the type of loop filter and bandwidth? I also had a quick question: The only...
  5. S

    Help with loop filter for FM transmitter

    I plan on AC coupling into the VTUNE pin of the chip.
  6. S

    Help with loop filter for FM transmitter

    So right now I am building an FM audio transmitter based on the ADF4360-8. I have the evaluation board for this device and what I am working on right now is changing the loop filter that they included on the board with my own that will work best for audio modulation. What they have included on...
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    Design broadband matching network for amp - beginner

    Hi, I am a beginner to RF design, but I want to know where to start when designing a broadband impedance matching network. I want to make 1W FM amplifier 88-108MHz using RD01MUS1 mosfet. I have the s-parameters, so what are the calculations I need to make a matching network. What type of...
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    Calculate dBm from dBuV without Ohms

    This is odd. At this point I am almost certain the output power is -8 to -10dbm because I tested a similar device with 118dbuv instead of 121dbuv like the first listed in the datasheet and it outputs roughly the same power. At this point I honestly don't care why as I've moved to the next stage...
  9. S

    Calculate dBm from dBuV without Ohms

    Hi, I've come across many datasheets for RF transmitter ICs where the power output is given in dbuv, but no ohms are given. Is it correct to automatically assume 50ohms when trying to calculate the power in dBm. In other words, I need to find power in dbm when I am only given dbuv? Thanks!
  10. S

    What is a good NEW PLL chip for FM transmitter?

    I want to use a PLL IC with the minicircuits POS-150 VCO for an FM broadcast transmitter. All the schematics I find use very old chips that are only on ebay from china and maybe fake (TSA5511, MC145170, etc.) I want a new chip that I might be able to get from a reliable source like digikey or...
  11. S

    ADF4360-8 FM broadcast transmitter

    I want to design a simple FM transmitter circuit, but also not compromise the spectral purity by using one of those all in one transmitter ICs. After hours of research, I've come to the conclusion that the ADF4360 is probably the best option for low component count and high spectral purity...
  12. S

    Reduce FM PLL noise

    I am using one of those all in one FM stereo transmitter chips. It works very well, but there is a lot of phase noise from the PLL. The chip's default crystal clock speed is 32khz, but the datasheet says the device can be programed for several crystals all the way up to 38.4mhz. Would increasing...
  13. S

    FM transmitter chip RDA5820 PLL unlocking?

    I have built an FM transmitter circuit using the RDA5820. (It is one of those all in one FM stereo transmitter chips). Anyway, it has a problem with what I think is the PLL unlocking after a few minutes of transmitting. It makes a loud popping noise and the carrier is shifting on the analyzer...
  14. S

    Modern DSP DDS FM transmitter schematic/tutorial

    I am looking to design/build a high quality FM broadcast transmitter. I already designed a simple transmitter with PIC controller and FM IC, but these are very low quality. The only schematics I can find are very outdated and use old chips from the 80s like BH1415F, TSA5511. I want a tutorial on...
  15. S

    Calculate total power from spectrum

    This would seem to be a pretty common question so I'm surprised I can't find any information on it. This makes me think I might not be thinking clearly. Anyway, how do I calculate the total RF energy in a spectral range? Peak and average power is easy, but how do I calculate total power (you...

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