Entry Scope that reads frequency good enough to do alignment on amateur radio  - Page 1
Forum section: electronics / testgear

author: powerstroke7.3
author_rank: Contributor
timestamp: September 03, 2022, 11:24:21 am
content: So the hantek DSO2C10 is not reading close enough and in some cases not at all. My broken tektronix 2247a still reads frequency quite well but I thought the hantek would also. Also reads low res like 10.255mhz rather than 10.255xxx mhz.Is there a cheaper scope like maybe a owon or something that will do this for me? I'm reading master oscillators and carrier osc and that type of thing.

author: tszaboo
author_rank: Super Contributor
timestamp: September 03, 2022, 11:29:59 am
content: That's not the main function of an oscilloscope. What you need is a frequency counter. Some scopes have this built in, but you are probably better off with a cheap used unit from ebay.

author: powerstroke7.3
author_rank: Contributor
timestamp: September 03, 2022, 11:51:51 am
content: I have some counters but they aren't accurate enough or sensitive enough. Old heathkit and some mighty fine junk (mfj) my tektronix 2247a if it was fully functional is all I need.I'm not sure what would be a good dedicated frequency counter these days.

author: RoGeorge
author_rank: Super Contributor
timestamp: September 03, 2022, 11:54:22 am
content: The proper tool for radio alignment/repairs would be a spectrum analyzer.There are plenty of frequency meters, some simpler designs for amateur radio (more or less just an Arduino with a display and some frequency dividers), others can be expensive standalone counters. Some are ready made, others are as kits for hams to build.Some signal generators also have counters, for example my DDS Rigol DG4102 has an input to measure frequencies with many digits, apart from the outputs that generates signals.To answer the question, Rigol DS1054z is an entry level oscilloscope that has a hardware frequency counter with 6 digits. Other models might have hardware counters, too, talking about DS1054z because this is the one I happen to have.

author: powerstroke7.3
author_rank: Contributor
timestamp: September 03, 2022, 12:04:10 pm
content: Quote from: RoGeorge on September 03, 2022, 11:54:22 amNice. I'll look for it. What do thru cost usd?

author: powerstroke7.3
author_rank: Contributor
timestamp: September 03, 2022, 12:05:21 pm
content: I have a nano vna...wonder if the mini sa spectrum analyzer is as good

author: David Hess
author_rank: Super Contributor
timestamp: September 03, 2022, 12:59:15 pm
content: Quote from: powerstroke7.3 on September 03, 2022, 11:24:21 amThe 2247A has a real 10 nanosecond universal reciprocal frequency counter tied to the 3 trigger generators so it can make integrated frequency and time measurements. Offhand I do not know of any DSOs with similar capability, although they should be able to duplicate it.The capability of the 2247A is roughly comparable to an HP 5315A or 5316A universal counter if you want to look for an inexpensive replacement. These universal counters use a 100 nanosecond instead of 10 nanosecond clock but that would not make a difference in your application. The Tektronix DC509 universal counter is practically identical, and might use the same timer/counter ASIC.

author: ledtester
author_rank: Super Contributor
timestamp: September 03, 2022, 01:11:56 pm
content: Quote from: powerstroke7.3 on September 03, 2022, 12:05:21 pmThe "guy with the Swiss accent" just did a video on this:How to Use a Vector Network Analyzer (VNA) to Test Antennas -- Andreas Spiesshttps://youtu.be/91ZRTFZ40rw

author: iMo
author_rank: Super Contributor
timestamp: September 03, 2022, 01:39:14 pm
content: It depends what kind of radio you want to align and how. Shortwave or VHF/UHF one?Even for shortwave rig you would need a counter with 1Hz or better accuracy provided you are measuring its VFO. The nanovna is not the best tool for aligning an VFO of a ham radio, imho.Another option is to use a calibrated generator (1-30MHz for shortwave), and to measure the beat, like 1kHz in audio, that could be done with a low freq counter which does 1Hz or better (ie a sound card)..

author: mag_therm
author_rank: Frequent Contributor
timestamp: September 03, 2022, 01:55:38 pm
content: I've set up the new GW Instek 1202B on the sig gen.It is reading sig gen 14.0740 MHz after 15min warmup as 14.0740 MHzIt reads down to about -44dBm where noise starts to be visibly about 10% of the signal, and the frequency measurement starts to jitter.I am not sure whether that noise is internal to scope or from the sig gen or 1 metre bnc-bnc cable.The FFT trace minimum resolution is 2.000 MHz/div.and the FFT horizontal position click stops are then in steps of 0.02 MHz or 20 kHz.Edit, the noise is at 62 MHz, FM band, and 125 MHz ( airport nearby)so I think it is getting into sig gen.Edit 2: A test later, replacing the Instek 1202B DSO with the vintage HP141T S.A. shows that the HP141T has approx 30 to 50 dB better screening againstunwanted QRN in the range 50 to 110 MHz, compared the the above results with the 1202B.

author: djsb
author_rank: Super Contributor
timestamp: September 03, 2022, 03:15:30 pm
content: Or there's the TinySAhttps://www.tinysa.org/wiki/

author: powerstroke7.3
author_rank: Contributor
timestamp: September 03, 2022, 05:49:19 pm
content: Quote from: djsb on September 03, 2022, 03:15:30 pmThat's what I meant when I mentioned the vna and mentioned "mini" sa on accident. Yeah I wonder if it's good enough?