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Re: Si5351 output power
Something to keep in mind in circuits that use multiple power supplies is power sequencing: It is important that the 5V comes on before the 3.3V and turns off after the 3.3V when the 3.3V turns off.
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Steven Dick, K1RF
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#478
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Re: Si5351 output power
Hi all Loading an Si5351A output at 50-ohms also affects phase noise. I did a study of Si5351A phase noise, particularly in relation to the QCX CW transceiver http://qrp-labs.com/qcx . One of the
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Hans Summers
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#477
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Re: Si5351 output power
If you read the datasheet, the Si5351 claims to have a 50 ohm output. But yes, it is primarily designed to replace cheap 4 pin crystal oscillators. Jerry
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Jerry Gaffke
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#476
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Re: What level math is in the RF design books?
Good news: Algebra for designing and biasing bipolar circuits. Not so good news: Partial differential equations for biasing FET circuits, though I¡¯d probably just copy an oscillator circuit rather
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Bob N1RC
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#475
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Re: Si5351 output power
It¡¯s a clock generator and was designed to drive a logical load, that is, a CMOS or TTL input, and definitely not a 50 ohm resistance. The first rule in a situation like this is to *read* the data
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Bob N1RC
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#474
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Re: 7 MHz Oscillator Ideas
I¡¯d grab a 40 meter tank circuit from one of the older handbooks for a cheap and cheerful solution. Or a DDS circuit like this
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Bob N1RC
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#473
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Re: 7 MHz Oscillator Ideas
Thanks for all the ideas gents, I need to get some parts from Diz and Rex and start experimenting. Hopefully after Christmas.
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JT Croteau <jt.tobit@...>
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#472
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Re: Si5351 output power
That ebay amp can drive 50 ohms with a whopping 10dBm, or 10 milliwatts. That works out to about 0.707 volts RMS on the output, less than your Si5351. It's meant for use in front of a receiver, or
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Jerry Gaffke
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#471
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Re: What it is this?
It has a 14mhz crystal, a transistor, a few passive components, a transformer, and then a two inductor output filter. So I'm going with Eric that it plugs into a larger assembly, and say that this
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Jerry Gaffke
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#470
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Re: What it is this?
No idea, but given the stacking header and part designations all in the 20's, it looks to be part of an assembly. A daughterboard of some sort. Maybe that'll jog your memory. Eric KE6US
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Eric KE6US <eric.csuf@...>
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#469
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Re: Si5351 output power
Jerry Thanks for the info. I need about 10 volts. What are your thoughts on this? https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F162854440017 73 Don ve3ids
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Don VE3IDS
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#468
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What it is this?
Hi all, I have gotten back into radio after about a decade. ?Finding my goodies I didn¡¯t complete. ?One kit I found doesn¡¯t have any documentation or any info on the board. ?The crystal is
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Kurt Loken <kurt.loken@...>
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#467
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Re: Si5351 output power
Maybe this 74ACT04N, $0.50 plus $10 shipping: https://www.mouser.com/ProductDetail/Texas-Instruments/SN74ACT04N?qs=sGAEpiMZZMtYFXwiBRPs03JnqncIqXT7 Ground pin 7 with a very short wire (or just bend
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Jerry Gaffke
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#466
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Re: Si5351 output power
Nick, Ah, I vaguely remember a discussion on the bitx20 forum about using a logic gate. Allison kicked it off with a discussion of crosstalk in the Si5351 outputs when they get loaded down: This
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Jerry Gaffke
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#465
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Re: Si5351 output power
On a related topic, I built a vfo with a nano and a 5351 to replace the vfo in a tube rig but I need more voltage to drive it. It will operate the receiver but is just on the edge for the TX. It will
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Don VE3IDS
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#464
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Re: Si5351 output power
Yet another correction, I should just go back to bed: Both the 6db and 3db pads are trying to terminate the oscillator and mixer with 50 ohms, but the 6db pad is doing a better job of it. This is at
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Jerry Gaffke
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#463
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Re: Si5351 output power
I think I would have gone for the power in the sine wave that's under those harmonics and divided the 0.8 Vpk by sqrt(2) to get the power of the fundamental. FWIW and regarding appropriate loading of
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Nick Kennedy
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#462
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Re: Si5351 output power
A couple edits are required here: < With capacitive coupling, the Si5351 is? effectively driving your?50 ohm load into 3.3/2=1.65 volts, < When a mixer says it wants 7 dBm, I believe that's defined
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Jerry Gaffke
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#461
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Re: Si5351 output power
Mike, I haven't made any such measurements, so you're ahead of me on that. I have heard in other forums that crosstalk and perhaps other forms of distortion creep in as the Si5351 output buffers get
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Jerry Gaffke
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#460
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Re: Si5351 output power
When building the DC40, Robin AC7LX recommended a 3db pad, and I implemented that. Works great. I wrote up my pad here: https://miscdotgeek.com/building-a-direct-conversion-receiver-part-4/ There's
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Ryan Flowers
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#459
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