#558b

Episode 558b
The calibration requires an external source, so I try and build the cheapest one possible and show how to do the calibration
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[@aciscarcab]

What do you think using the 300MHz armonic (from the 30MHz Cal. output build in) to calibrate? When you activate the 30MHz Cal. output, and you put the SMA bridge, the same signal is present in both High and LOW inputs.

[@erin19030]

The low port is all I ever use for radio IF alignment.

[@davidaz4933]

You can just output a square wave out of the oscillator like I did Choose the desired harmonic Add at the output add a saw filter with center frequency you want for example IF SAW Filter 307.36MHz(BW=20MHz) And that way you don't have to worry about the other harmonics

[@PapasDino]

Maybe the designers of the NanoVNA and SA would consider a dedicated RF signal generator (have to clean up the synthesizer probably but if it's dedicated it''s probably doable) that matches the series...that would make for a real beginner's RF bench for probably less than $200.

[@IMSAIGuy]

There is a cheap RF source that I have on order. Yes a complete RF bench on the cheap is my goal.

[@ErikKaashoek]

The tinySA is a RF signal generator too. You can also use the nanoVNA with some attention for high power calibration

[@IMSAIGuy]

@@ErikKaashoek I'm trying to do a tracking generator. I've turned on the LO output and sent to a mixer. the mixer has 433.9MHz input. so the IF is sweeping at the correct frequency as seen by a second spectrum analyzer. I can't get the TinySA to show the information. Any other settings needed?

[@ErikKaashoek]

@@IMSAIGuy YOu have to enable the LO output as described here: tinysa.org/wiki/pmwiki.php?n=Main.SETTINGS and the total setup looks like this: tinysa.org/wiki/pmwiki.php?n=Main.Mixer

[@IMSAIGuy]

@@ErikKaashoek I got it working. Was surprised at the high level of the LO out. It actually worked fine turned off. about 10dB leakage around the switch. otherwise I used a 20dB pad as you had. I also found that the IF frequency was 433.8 or at least got more signal there my mixer was set to 433.8. if my mixer generator is 433.9 then I have to use expert mode and set IF to 433.9 inside the Tiny

[@bobcraig3827]

You actually calibrated the High input to -1dbm. Look at your display: Lo reads -31 without attenuation. High also reads -31 but with 30 db internal attenuation switched in.

[@aciscarcab]

Bob Craig , The internal attenuation is "transparent" in the measurement obtained. Internal attenuation is used only to make the measurement more accurate by allowing the spectrum analyzer circuitry to handle signals of the appropriate power, and in the end, the value obtained by the power detector is added internally to the value of the internal attenuation used to display the actual power value on the screen..

[@soulrobotics]

perfect!

What do you think to replace oscillator with SI5351 that supports frequency output between 0.0025 and 200 MHz. SI5351 Module cost 3 euro (shipped) + PC or Arduino / Raspi. Output power is between 12mw and 20mw*. Charge pump have a 3 settings Low 2mA, Medium 4mA and High 8 mA. The drive strength is the amount of current into a 50Ω load. 2 mA roughly corresponds to 3 dBm output and 8 mA is approximately 10 dBm output.

[@IMSAIGuy]

200MHz is not high enough

@@IMSAIGuy so Si5351 harmonics are not to strong enough?

[@IMSAIGuy]

@ don't have experience to say. is it a square wave or sine wave. if square wave then should be OK

@@IMSAIGuy yes, it is square wave without any types of filters. Produces lots of harmonics. Cristal oscillator is cheap when you harvest it from other boards but si5351 is more versitale. I assume that harmonics levels are usable.

[@frankreal2258]

Hello, sorry if I bother you but your help is needed for my 100$ rf lab, please come across one old HP power meter and I stripped off the 50Mhz reference source the can whose in good condition the 50mhz trimmer had one sticker calibration seel, I don't touch! (is the only reference standard can I got). I came across one Chinese power meter with a similar chip on your video I watch all your video MAESTRO. Some help for the calibration step es.. offset on de beginning of reading scale and reference on de end or on the midle? the circuit got some linearity response and this encouraging. thank you in advance.

[@IMSAIGuy]

It will be best to create a calibration table as things will not be linear. Unfortunately, you need a power meter to build a power meter. If you can calibrate a 10dB range, you can transfer that range by calibrated attenuators. If you can measure say -20dBm to -10dBm, then you can measure anything bigger by adding attenuators to the input. The other direction is much harder. if you can create -20dBm to -10dBm then you can use attenuators to drop that source power lower and then use the power meter to try and measure. so use -20dBm to -10dBm with 10dB attenuator to create -30 to -20 and repeat, each range can be calibrated to fit all ranges into one line. the bottom of one will be the top of the next. I designed a power meter that would run from -70dBm to +20dBm (don't try this at home :) ) The cal source is only 50MHz so you need to figure out how to extend that to other frequencies. how to measure power of a 1GHz source? We used a very expensive VNA to do that and stored that cal data.

[@frankreal2258]

@@IMSAIGuy, I realize your expertise on the subject this is the reason for my question to you, I think to get other power references on a different frequency so I came across one RF power detector from CRISTEK part number: CPDETLS-4000 from 10Mhz to 4Ghz- they give one reference table from Mhz10- 50-100- 500- 800- 915- 1G- 1.5G -2G- 3G.-4-G with the power of -10dBm -8, -6, -4, -2, 0, +2, +4, +6, + 10. I think using this detector for the transfer reference and the 10Mhz and the 50mhz 0dBm reference (hope to find one at 500Mhz and 1 Ghz) the idea is one reliable measurement, not a Hi-end instrument. my email is: [e-mail] the CRISTEK detector is reliable? there is another way to doing?

[@IMSAIGuy]

@@frankreal2258 no that is not very accurate. how accurate are to trying for? what test equipment do you have? generator, spectrum analyzer, scope, attenuators, vna,

[@IMSAIGuy]

what range of power are you trying to measure

[@IMSAIGuy]

are you trying to design a power meter or just make measurements

[@timbelson9522]

Just double checking as i seem to miss it every re watch but the capacitor connects pin8 (output) to center pin of sma connector only , wanted to reconfirm before i build and power one of mine up 😅

[@IMSAIGuy]

the oscillator ground is connected to the outside of the sma and the capacitor goes between the oscillator output pin and the center conductor of the sma

[@IMSAIGuy]

make sure you use an attenuator

[@timbelson9522]

@@IMSAIGuy definitely will be sure to use attention, i thank you actually for a Video of yours in not so distant past saved me blowing up my Nano vna with a small 19db gain but for really low power amazon ones, had i not found your channel id jave probably made expensive mistakes, so thank you

[@timbelson9522]

@@IMSAIGuy thanks for clarifying, ill be sure to keep your advice and tips in mind especially with my current diy ish upconverter for my sdr😊 happy new year by the way

[@IMSAIGuy]

yes

[@cozarmx]

Hello, I have read some articles and it looks like the analyzer that you have on this video is a clone.

[@IMSAIGuy]

It is not. I had an original unit sent to me by the inventor in holland.