Output Power Meter in Siglint 1032X-grade Generators? - Page 1
Forum section: electronics / testgear

author: NT0Z
author_rank: Regular Contributor
timestamp: January 17, 2023, 10:18:27 pm
content: Hi, gang,I need to build several 8307-style log-based RF power meters, and I want to find an easy way to properly calibrate the 8307 units.Years ago, when I had access to an RF lab, I'd simply connect the home-brew power meter to the calibrated output of a Marconi or HP (big buxx) signal generator, mark the appropriate meter deflection spots on the meter face, and boom!I'd like to be able to do that again, and I was wondering whether the output of something like a 1032X is metered/adjustable, and how accurate it might be for my purposes. I am considering the purchase anyway, for RF generation and to use as a frequency counter (I have a 10-MHz SDO to "discipline" it).I also have a Rigol 815 spectrum analyzer with tracking gen. I haven't looked into it yet, but I may simply be able to generate a tracking signal, measure it on the SA, and swap the SA input for the 8307 input to get the reading. If anyone knows whether this will work, please let me know.Ten years ago I stopped buying radios and started buying test equipment. Now I obviously have to learn better how to use it to do specific tasks...As always, thanks for your help.Kirk, NT0ZRochester, MNwww.stealthamateur.com

author: tautech
author_rank: Super Contributor
timestamp: January 18, 2023, 12:02:13 am
content: Welcome to the forum.What resolution/accuracy over what frequency range ?SDG1032X while one of my favourites is not really up to the task compared to the specs of SDG2042X.Look up Output Characteristics:https://int.siglent.com/u_file/download/22_06_23/SDG1000X_DataSheet_DS0201X_E01I.pdfhttps://int.siglent.com/u_file/download/22_07_28/SDG2000X_DataSheet_DS0202X-E02G.pdfSDG2042X in particular can offer better flatness than a SA TG as when we Normalise any nonlinearity is removed from the TG sweep.

author: NT0Z
author_rank: Regular Contributor
timestamp: January 18, 2023, 03:26:37 am
content: Well, I guess, in this case, the accuracy of the output wave in terms of power is the most critical. The 8307 measures power in the -70 to +10 dBm range (approx), so if I could nail a level near 0 dBm I guess I could do other calibration points with a set of attenuators?It would certainly be handy to simply spin the dial and tick off each 1 dBm mark on my analog meter scale like I did back in the day.The 8307s are quite linear to 500 MHz, which exceeds my needs.Thanks,Kirk, NT0Z

author: xrunner
author_rank: Super Contributor
timestamp: January 18, 2023, 04:01:17 am
content: Hello NT0Z,I built two power meters using an AD8310 and AD8307 and an Arduino for a controller. The 8307 project starts about here in another (long) thread -https://www.eevblog.com/forum/rf-microwave/cb-and-ham-radio-techs-love-their-bird-wattmeters/msg4329763/#msg4329763Don't know if it will help you or not.You can buy a used hp 437B without a sensor and it will have a very accurate 0.0 dBm reference. Might cost between $40 and $60, then as you said use attenuators to reduce power as needed. Good luck.

author: switchabl
author_rank: Frequent Contributor
timestamp: January 18, 2023, 05:51:57 pm
content: Quote from: tautech on January 18, 2023, 12:02:13 amCan you expand on that? Both datasheets appear to share the same ±(1% + 1 mVpp) accuracy (@1 kHz) and ±0.3 dB flatness (up to 60/100 MHz) specifications.

author: Performa01
author_rank: Super Contributor
timestamp: January 19, 2023, 10:46:22 am
content: At least the SDG6000X should be well suited for calibration purposes on a hobbyist level. I don't think there is a significant difference to the SDG2000X - not quite sure about SDG1000X though.Demonstration of the amplitude accuracy (reply #162):https://www.eevblog.com/forum/testgear/siglent-sdg6000-series-awg_s/msg2621457/#msg2621457

author: xrunner
author_rank: Super Contributor
timestamp: January 19, 2023, 12:35:07 pm
content: Quote from: NT0Z on January 17, 2023, 10:18:27 pmI tested it today. At 100 MHz zero span, the DSA 815TG tracking gen was set to 0.0 dBm, and I measure -0.43 dBm output.

author: NT0Z
author_rank: Regular Contributor
timestamp: January 20, 2023, 01:03:41 am
content: Thanks for making that test. I appreciate your help.For my purposes I can live with a rough correlation or 0.4 dB.Q: Was the tracking generator a separate device, or was it the TG built into the 815?My 815 has the TG, and I also have a generic 15-MHz arbitrary waveform gen that was sourced by a friend from Ali or eBay. I also have a weak-signal RF source from Elecraft that outputs on 6 meters (I think) with a "significantly known" level (I just don't know what the level is off the top).--Kirk, NT0Z

author: xrunner
author_rank: Super Contributor
timestamp: January 20, 2023, 01:29:50 am
content: Quote from: NT0Z on January 20, 2023, 01:03:41 amNo problem.QuoteBuilt-in.

author: bdunham7
author_rank: Super Contributor
timestamp: January 20, 2023, 02:03:14 am
content: Quote from: NT0Z on January 20, 2023, 01:03:41 amI can't comment on the SDG1000X, but my SDG2042X (now SDG2122X) is accurate enough to calibrate moderately good DMM AC ranges and is flat enough to 100MHz+ that I can't see any significant error on my HP 438A RF power meter. I don't have any sensors right now and my CMU200 is packed away under the bench or I'd show you some results, but my observations of my unit tell me that it is more than flat enough for what you are looking to do. IIRC it is amost perfectly flat out to beyond 50MHz, then it starts to roll off a tiny bit as you cross 100MHz.Connected to a 6.5 digit DMM (Fluke 8846A) I can select outputs from -40dBm to +10dBm at 1kHz and the meter will indicate the same within 0.02dB. It seems to be about 0.01dB high when first turned on and then .02dB low after a few hours. This is approaching the accuracy specs of even a very good DMM, so much better than an RF power meter or SA or anything that works over a large BW. Obviously YMMV and a different unit is only guaranteed to meet the specs listed, but I think what I see with mine is pretty typical. All you would need to cover your range is a single 30dB attenuator.

author: NT0Z
author_rank: Regular Contributor
timestamp: January 20, 2023, 02:08:04 am
content: Dang, that's a nice unit -- but a bit too far from my casual purchase price point.If I had to burn "tax deductible money," yes, but 2022 wasn't one of those years...As always, thanks,Kirk, NT0Z