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Matt kd4pbs · 8th Mar 2021, 12:18 am

I thought I had seen a spec from an NEC datasheet stating the 2SC2150 had a ~5dB nf. Of course that was a max rating.

I think you're right on the input plot. Most likely this is because I do not have a SMA cal kit with polynomials known. Then again, it is quite possible that at least calibrating it with what I do have would give better response than calibrating to the N connectors and using the N-SMA transitions I have on hand, but it's from one of those $1.98 mini VNAs that I just had to play with. The cost of a genuine HP SMA cal kit is way more than I paid for this spec an.
I guess I could try tacking on a resistor to the ends of those traces to make 50 ohms, and go from there, but as you can see in the pictures, no resistor was on there and unless the substrate resistors changed that greatly, they most definitely are not 50 ohms.
I agree that something isn't quite right. I'll certainly have something to do until the regulator transistor comes in.
Thanks bunches, Jeremy!
Regards,
Matt

8th Mar 2021, 12:18 am	#81
Matt kd4pbs Tetrode Join Date: Mar 2021 Location: Raleigh, North Carolina, USA. Posts: 62	Re: Spectrum Analyser TR4172 I thought I had seen a spec from an NEC datasheet stating the 2SC2150 had a ~5dB nf. Of course that was a max rating. I think you're right on the input plot. Most likely this is because I do not have a SMA cal kit with polynomials known. Then again, it is quite possible that at least calibrating it with what I do have would give better response than calibrating to the N connectors and using the N-SMA transitions I have on hand, but it's from one of those $1.98 mini VNAs that I just had to play with. The cost of a genuine HP SMA cal kit is way more than I paid for this spec an. I guess I could try tacking on a resistor to the ends of those traces to make 50 ohms, and go from there, but as you can see in the pictures, no resistor was on there and unless the substrate resistors changed that greatly, they most definitely are not 50 ohms. I agree that something isn't quite right. I'll certainly have something to do until the regulator transistor comes in. Thanks bunches, Jeremy! Regards, Matt Last edited by Matt kd4pbs; 8th Mar 2021 at 12:26 am.