EMRFD Message Archive 11539
Message Date From Subject 11539 2015-08-26 08:42:06 Ashhar Farhan Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer People,continuing on the thread of recent exchanges about the QST spectrum analyzer, here is some fresh meat.For the last few years, I have been erratically putting a spectrum analyzer together based entirely on the W7ZOI/K7TAU design.I am happy to say that the end result is a really easy to put together specan and it can be built without any special components or equipment for less than hundred dollars.Here are the details : http://hfsignals.blogspot.in/p/specan-reboot-of-w7zoi.htmlBriefly, if you don't want to click on the link above:1. This specan has an Arduino controlling it. The local oscillator is an Si570.2. No oscilloscope. The display is on the PC. There is a built-in LCD display to make spot measurements.3. Si570 gives us very high stability, as a result the narrow bandwidth is less than 1 KHz.At -30dbm (one micrwatt) input, the dynamic range is in excess of 80db without any spurs.With this, the specan is also capable of measuring fairly close-in IMDR (inside the passband of a transmitter, for instance). But it is slow for a full scan.However, it is quite fun and easy to build. it takes more than a few evenings. but if i can get there, so can anyone.If anyone has an questions which you think might interest the group, please ask them here, otherwise, you may send them to my email-id.I'd like to thank wes for indulging in my stupidities through the months, getting this one going. he has been the most patient elmer one could hope for, in addition to being the best 'in the trade'. (grin!)towards the end of this project, I was so tired to write the paper that it needed bill meara to finish the editing. all the grammatical errors, technical mistakes and the main reason for it to not work if you ever attempt it must be attributed to him (kidding).- farhan 11542 2015-08-26 15:14:15 Sandeep Lohia Re: Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer off topic
many thanks for 100 Mhz oscillator based on John Stephenson's design.
Is it possible to modify same for something in between 150 to 200
MHz ( MCLK for AD9851 ) without enabling old x6 option as to
What components value do I need to change? L 11 ? L 10 ? 10 PF ?
I don' t. have QST article but got in my junk BFW10 / 11. J310, box
full of. XTALS & an RTL. SDR,
Also why U using 4 X 50 ohm ( actually 8 x 100 ). in your' s
resistive bridge for balanced line tuner? they should be just 3 to
complete, another 50 ohm I mean antenna itself. or it's a print
mailed from mob.
Please encourage recycling, reuse or repairing of E-waste.
░7░3░ ░d░e░ ░V░U░3░S░X░T░
11543 2015-08-26 15:46:58 John Marshall Re: Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer Sandeep,
As you correctly point out, the antenna/tuner input (T1) is the fourth leg of the bridge. The two resistors (R) connected to the diode (D1) are not part of the bridge but serve as a termination for the detector.
11544 2015-08-26 17:59:28 firstname.lastname@example.org... Re: Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer
two parallel 100 ohm resistors are of 2 watts each. hence they can handle 4 watts of dissipation. under perfect balance, this bridge should be able to handle 16 watts continuously or about 30 watts intermittently.
given that we use touchy devices like the IRF510s, i elected for a resistive bridge to provide fair to good termination towards the equipment side.
if you have more questions, send them offline.
11545 2015-08-26 21:51:48 Adrian Scripcă Re: Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer Hi Farhan,I'm glad the sudden resurected interest in SA made you rush share SPECAN with us :) SPECAN's idea is something that I've been pondering on quite a lot of time, too, though I've been put off by the slow sweep speed of current digital solutions. SPECAN complements the W7ZOI/K7TAU SA in allowing digital capture of the analyzed spectrum for publishing, extracting complex measurement like 3dB peak, measuring intercept points, etc. Great job!Some questions:1) - what would be the effect of using a Si5351 as VFO instead of Si570? Si5351 breakout boards seem to become available everywhere and they are really cheap. It might proove to be a good option if it does not affect the quality of the measurements in a considerable way2) - how does power calibration work exactly? Building an XTAL osc and measuring its input in 50 ohm is fine but how does one obtain the insertion loss of the narrow/wide filters?Thanks,Adrian, YO6SSW 11546 2015-08-26 21:59:16 Ashhar Farhan Re: Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer Adrian,The Si5351 had pretty bad spurs. I suspect the noise floor was higher too as seen by rise in the baseline of empty scans.On the other hand, the caliberation is quite simple if you keep in mind that the signal gain is different between the narrow and wide filters. They calibration is entire in the software. Ther 11547 2015-08-26 22:01:32 Ashhar Farhan Re: Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer oops, i hit the send button by mistake. continuing ...there are two constants in the specan's arduino source. these must be adjusted to reflect the correct values. this is more round about than plugging in a known source and pressing some 'calibrate NOW' button but it works. i hope someone makes this version and adds a calibration patch to the arduino code.- f 11548 2015-08-26 22:17:34 Adrian Scripcă Re: Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer Hi Farhan,there are two constants in the specan's arduino source. these must be adjusted to reflect the correct values.That's not a problem (hardcoding the values in the code), my question is *how* do I know the correct values? Let's take a concrete example: say I build an XTAL oscillator for 10MHz which measures -10dBm (200mV peak to peak in 50 ohm when measured with the scope).What then? I need to tweak the wide/narrow filter compensating values in the source code so that I get ... what output?Thanks,Adrian, YO6SSW 11550 2015-08-26 22:26:46 email@example.com... Re: Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer
you tweak them until you read -10dbm on the lcd display.
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11551 2015-08-26 22:35:42 Adrian Scripcă Re: Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer Ok, I feel dumb now :) I assumed the correct values to be read would be different with respect to the filter used, due to insertion loss, bandwidth and gain variations of the filter blocks. I was braindead there for a moment. Thanks for clearing that up!Adrian 11552 2015-08-27 08:00:28 Nick Kennedy Re: Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer That's quite an achievement! It's going to be hard to avoid adding this one to my backlog of things I need to build.The blog hardly mentions the effort that went into the PC interface software. I'm sure it took some doing too.73-Nick, WA5BDU 11577 2015-09-03 20:51:49 Steve Ratzlaff FS: book--Zverev's Handbook of Filter Synthesis For Sale: "Handbook of Filter Synthesis" by Anatol Zverev. $35 shipped
Paypal, cash, check, money order.
11579 2015-09-04 07:09:30 Jim Kortge Re: FS: book--Zverev's Handbook of Filter Synthesis 11581 2015-09-04 08:37:12 Steve Ratzlaff Re: FS: book--Zverev's Handbook of Filter Synthesis Hi Jim,
You're third in line; I'm just up and checking email but you can
consider the book to be sold already.
11863 2015-10-29 09:10:48 musacokan Re: Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer Hello FarhanI did Sweeperino and SpecAnbut SpecAn PC program is not working.Action-> Connect-> com6 (I use the Arduino)the program immediately quits.YouTube also different program you use.We used different.I'll be glad, if you help meI add the YouTube video link.Musa Çokan TA3CM 73 11864 2015-10-29 12:26:36 Ashhar Farhan Re: Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer there does seem to be a different version on the net that is not working. i will upload my current version (the one i am using right now) by tomorrow. it is best if u could compile it from the sources on github.- f 11866 2015-11-02 08:45:19 musacokan Re: Specan - A reboot of the W7ZOI/K7TAU spectrum analyzer Hello FarhanI'm waiting.Do your loading or link.Thank youMusa Çokan TA3CM 73