RF-Kit.de RF2K+ PS report

NC3Z
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Joined: Sun Oct 29, 2017 8:57 pm
Location: Merritt, NC

RF-Kit.de RF2K+ PS report

Postby NC3Z » Sun Dec 17, 2017 12:45 pm

Just got my new to me 200D operational and have it driving my new RF2K+ which has a built in sample port @ -62dBm. Worked right off the bat with no fussing and no additional attenuator. The PSDR ATT on TX settles right at 15dB and get the green Correcting and green Feedback indication.

Nice and simple integration for a legal limit plus solid state amp.
Gary NC3Z
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Tony EI7BMB
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Re: RF-Kit.de RF2K+ PS report

Postby Tony EI7BMB » Sun Dec 17, 2017 1:58 pm

Nice looking amp
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w-u-2-o
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Re: RF-Kit.de RF2K+ PS report

Postby w-u-2-o » Sun Dec 17, 2017 4:20 pm

I am definitely lusting after one of those! Jealous! :mrgreen: If I had 240VAC in the shack I'd already have one! Best thing on the market right now!

If you are getting 15dB of step atten., that implies you were operating at 1KW:

60dBm - 62dB = -2dBm at the RF Bypass input connector.
Less 15dB of step atten. nets you -17dBm at the output of the step atten. + 20dB of pre-amp gain, resulting in +3dBm at the input to the ADC. +3dBm is the target value that PureSignal auto attenuate shoots for.

Were you running 1KW when obtaining those readings?

I'd definitely recommend anyone ordering one or putting one together to try to obtain 50dB coupling factor. For older radios like the 100D and 200D this results in a better feedback-to-crosstalk ratio. On the newer radios, the 7K and 8k, where the pre-amp is only 16dB gain, this will net you more dynamic range when running lower power levels, i.e. you won't ever bottom out the step attenuator.

Consider if you were going to run 100W, perhaps on 60M, or some other reason. That's 50dBm. Less 62dB that equals -12dBm. Plus the 16dB of pre-amp gain, that equals +4. In such a case the step attenuator would be set to 1dB. Thus at any power level less than 100W the PureSignal auto-attenuate algorithm will be unable to obtain the correct feedback level. I suppose you might think "Who cares, at less than 100W I don't need PureSignal." Maybe, maybe not. If you go barefoot now you are still getting significant IMD from the internal radio amp. Anyhow, easily avoided if the coupling factor is set to 50dB, and that's really where it should be.

73,

Scott
NC3Z
Posts: 58
Joined: Sun Oct 29, 2017 8:57 pm
Location: Merritt, NC

Re: RF-Kit.de RF2K+ PS report

Postby NC3Z » Sun Dec 17, 2017 4:42 pm

Yes at 1000W I get 15dB, when I just tested at 500W it was 12dB.

I have calibrated the PO of the 200D to 25W max.
Gary NC3Z

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