Ten Dollar PIC 100khz-2.4ghz Frequency Counter

[paulie]

I recently received one of these:

http://www.ebay.com/itm/171506884137?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I paid 10$ shipped on Aliexpress but same as the one for $12 and change on Ebay. Listing says temperature controlled oscillator but there don't seem to be anything like that on the board. May be a great deal but I can't find a PDF or link to user manual let alone schematic or code. No idea what the buttons do or screen options mean. Anybody have any experience or more iinfo on these?

ps. More photos:

[paulie]

I did find some vaguely readable text on another site but not really very helpful:

Green 0.1-60MHz 20MHz ~ 2.4GHz RF Signal Frequency Counter Cymometer Tester

Description:
With Microchip's PIC16F648A, 2.4 GHz frequency meter.
Using temperature-compensated voltage controlled crystal oscillator (2.5 ppm VC-TCXO).
Unique gate control and precise time algorithm (non-timed interrupt).
Gate (display refresh) time 0.01 seconds / 0.1 seconds / 1.0 seconds, real-time display frequency value.
Single-ended input design, three-channel frequency measurement (low channel / high channel / Auto Channel).
Dual frequency design, value and IF / down mode can be preset separately.
Using eight 0.56 inches high brightness digital display, eight adjustable brightness.
Circuit is simple and reasonable structure, two-button control, simple operation.
The settings are automatically saved, boot directly call.
Descriptions:
1 Gate time
0.01 S
0.10 S
1.0 S

2 Measurement channels (channels are low impedance)
low channel
Measuring range: 0.1 MHz ~ 60 MHz
Accuracy: ± 100Hz (0.01 1s gate time)
± 10Hz (0.1 seconds gate)
± 1Hz (1.0 seconds when the gate)
Low channel sensitivity:
0.1 MHz ~ 10 MHz: better than 60mVPP
10 MHz ~ 60 MHz: better than 60mVPP
60 MHz ~ 75 MHz: Not tested

high channel (divided by 64)
Measuring range: 20 MHz ~ 2.4 GHz
Accuracy: ± 6400Hz (0.01 seconds gate)
± 640Hz (0.1 1s gate time)
± 64Hz (1.0 1s gate time)
High channel sensitivity:
20 MHz ~ 30 MHz: better than 100mVPP
30 MHz ~ 60 MHz: better than 50mVPP
60 MHz ~ 2.4GHz: not tested

Auto Channel
Automatically selected according to the input signal frequency high or low channel channel, identifying the frequency of 60 MHz. Such as when the input signal amplitude is greater than 60 MHz shortage can not automatically select high channel, the channel should manually select high frequency measurement.

3,IF settings
Independent double-IF design, adjust the minimum frequency step of 100 Hz, frequency range 0 ~ 99.9999 MHz, can be set to increase or decrease the IF frequency mode.

4. Frequency reference
Using 5032 package 13.000MHz Warming voltage controlled crystal oscillator (VC-TCXO), frequency stability of ± 2.5 ppm.

5. Operating voltage
DC Input: DC 9V ~ 15V (with reverse polarity protection)

6 Current
Maximum 160 mA (test conditions: ? DC12V power supply; ? red LED; ? eight brightness)

7 Eight LED display, the highest display eight digits.

8 Eight LED brightness is adjustable, factory set to maximum brightness.

9 Physical Dimensions,Length × width × height: 125.5 mm × 25.5 mm × 21.5 mm

10. Component quality 46 g (NW)

11. Onboard Interface
DC IN (Power Interface): HX2.54-2P socket
RF IN (signal input): HX2.54-2P socket
ICSP (programming interface): 2.54-6P Pin

[joeqsmith]

I recently received one of these:

http://www.ebay.com/itm/171506884137?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I paid 10$ shipped on Aliexpress but same as the one for $12 and change on Ebay. Listing says temperature controlled oscillator but there don't seem to be anything like that on the board.

temperature-compensated voltage controlled crystal oscillator  (2.5 ppm VC-TCXO).

Is the small metal package you show not the TCXO?

[dannyf]

Is the small metal package you show not the TCXO?

S/he doesn't know.

[dannyf]

They couldn't tell a tcxo from an ocxo? Possible.

[paulie]

I do know the small metal can is not TCXO. It says "13.000 A545SA KDS 411" which, judging from other similar KDS parts in my stock, is not temperature controllable but just a generic SMD crystal oscillator. Also unlikely any commercial TCXO would be that tiny?

ps. Probably typical chinese hype. Not worth opening a case though if I can get some use out of it. I'm surprised there are not more people out there familiar with this device because AFAIK there is no equal anywhere near this price range.

[Howardlong]

No problem in getting TCXOs in small packages like that. I use 2.5x2.0mm TCXOs in my products, 2.0x1.6mm is becoming increasingly available too.

[paulie]

Ok, so maybe these other KDS parts I have are also TCXO. Surprising there are not more zeros in the Mhz then. Anyway I would love to take advantage of this extreme accuracy if there were some hints around on how to use this thing. Many options and screens but no documentation.

[Marco]

You can get the VFD one for a couple bucks more.

Any way, found some schematics and docs. How's your Indonesian?

[paulie]

Thanks. Those diagrams help a lot with the hardware and maybe those flow charts too. Indonesian is Greek to me but a lot better than the Chinese docs that the seller just sent me. Amazing there's no action around here on that. I guess they are right about the east/west technology gap changing.

BTW I do like LED much better than VFD but if there was more info to be found there might learn to tolerate.

[xrunner]

Anybody have any experience or more iinfo on these?

I got one. It seems to be fairly accurate. I tried it on the 140 MHz and 440 MHZ ham frequencies and it was reading the correct freq. You can find a Chinese manual out there somewhere and run it through Google translate. I'll try to find what I got tomorrow.

2.54mm pin header for 2.4GHz? Kidding me?

LOL - yea I was a little disappointed with that when I got it. Should have done an SMA

[DanielS]

I guess someone must still be making cheap LED displays and digit drivers of some kind.

Who uses digit drivers these days? Much simpler to use an MCU for both the segment driver and address decoder in most cases, especially when the MCU is already needed for other stuff to start with, such as (problably) a MHz+ counting input, the count "gating", gating period selection, polling of the external pre-scaler at said gating, etc.

[rs20]

Temperature compensated XOs and temperature controlled XOs are different things. OP said it had the latter, the quote from #2 proves it's the former.

[Lightages]

Hmmm, $10-20 for a TCXO 100KHz to 2.4Ghz counter with LED or VFD? 2.5ppm accuracy? Sounds like a deal! Too bad I can't see any specs on the sensitivity for the 60MHz to 2.4GHz range. Does it even work up to 2.4GHz?

Still not a bad deal for someone who needs a counter and can't spend big bucks. There is more needed to make it useful of course. It needs a power supply if you don't want to use a battery or the lab PS. It should have a shielded enclosure with the needed switches and BNC or SMA connector and the proper cabling to the input front end as close as possible. Another problem is the input impedance. The specs only say "low impedance". This doesn't mean too much. It would cost probably another $50, or even more to make a stand alone instrument.

xrunner, can you measure the input impedance of yours?

[Marco]

I posted a link to the schematics before.

Input impedance is going to be nasty at the high frequency range, 4 1n4148 and two BF998R gates in parallel ... BF998R's which are connected in a really bizarre way by the way.

[rs20]

Regarding input impedance, how much does a high-impedance input 100kHz - 2.4 GHz buffer cost? Don't really know anything about high frequency, but I assume that's a module/block you can buy?

[paulie]

Temperature compensated XOs and temperature controlled XOs are different things. OP said it had the latter, the quote from #2 proves it's the former.

Re-reading posts you may see what I actually said was doubtful it had either. Those quotes don't prove anything except to the very gullible. For example use of the word "Warming" in one part of the spec from post #2 implies OCXO not TCXO.

Elsewhwere in the spec use of the term TCXO only adds confusion. I personally know the difference having designed and worked with different versions of both ( https://www.eevblog.com/forum/projects/worlds-smallest-cheapest-diy-temperature-controlled-oven/ ). I was surprised TCXO are available in 5032 even owning a reel of similar KDS inherited from my day job. Thanks to Howard I'm a little more up to speed on package variations.

[paulie]

Who uses digit drivers these days? Much simpler to use an MCU for both the segment driver and address decoder in most cases,

Actually for small number of digits like here the 7seg LED is much cheaper, about a 5-10 cents each. Fraction of a Hitachi type LCD anyway. And generally better visibility.

As far as driving direct there are nowhere near enough I/O to do that. Next size MCU up that can costs about 3x more. We don't have a schematic for the LED version but I do see a chip hidden under the display which might be the ubiquitous 74HC595 port expander. There's also an inaccessible pot under there, maybe brightness, which don't seem too bright to me.

[bingo600]

I posted a link to the schematics before.

Input impedance is going to be nasty at the high frequency range, 4 1n4148 and two BF998R gates in parallel ... BF998R's which are connected in a really bizarre way by the way.

Any chance of getting the info attached here ?
I'm not a FB user , and will never be

/Bingo

[Marco]

You don't have to log in ... you'll run into a bit of facebook js on tons of pages you visit, no reason to be afraid to simply visit the website.

Here's the frontend though.

PS. I think the BF998 will be little more than a couple of capacitors at 2.4 GHz.

[codeboy2k]

Here's an imgur album of all the pictures from facebook.

http://imgur.com/a/iENmk

[paulie]

Well I've had a chance to check this counter out against 24 pcs Raltron RTX-231 and 2pcs Vectron T1175 20mhz TCXOs and they all agree within 2 counts (1ppm). Even over a few degrees temperature variation which amazes me. This is just about the best $10 I've spent in some time. Too bad it stops just short of being able to measure 32khz watch crystals. This would make it 10x more useful.

I managed to figure out the bottom button scrolls sample window/resolution and filter and brightness menus. Not being fluent in Indonesian or Chinese I'm still not sure what the "Bit Set" (1f) function is for. Anybody have a clue?

[codeboy2k]

I don't have the unit, but google translating it I think it has something to do with the gate,
or display of the gate, and it might do something with the decimal points that are used to display the gate

Translate says: (my comments in blue )

ON: right numbers menu, bits last blanking  (decimal point blanking? blinking? gate display? )
OFF: normal view

purpose: (1) the last blanking bit beat  (  blinking gate display in the last decimal point ? )
figures to enhance the visual effect   
  (2) When the gate 1S megabit and gigabit screen when 0.1s
              ( when 1S gate, the display is MHz, when 0.1s gate, the display is GHz ) 


They wrote blanking but perhaps they mean blinking.

[xrunner]

Here's one in action. I'm transmitting on 449.500 MHz with 1 W and you can see what 's reading. If I attach a better antenna to it, it can correctly read the frequency of HF transmissions from my rig transmitting from an outside antenna while the unit is sitting on my workbench.

I attached a text document that came out of Google translate, it's nasty ugly but you can make sense out of the menu system if you have the document open and have one of the units in your hand to play with.  I've never found an original English manual anywhere.

[paulie]

Thanks for the text file. For some reason it came out better than the one translated from the one I was sent by the seller. Maybe the source was better, IDK. I was able to see that you can set an offset for the digits by using  the "IF" menu but still don't know what the purpose of that is. Also no idea what the "]" menu is for. I'm just not good at this RTFM stuff even in english.

BTW I also have one of those Baofeng radios. Unbelievable deal for the $16 I paid on Ebay. Very sensitive RX but the TX part is technically not quite legal here in the USA even if you use only the FRS or the other general walkie talkie band or even if you have a Ham ticket. Used responsibly though no harm done.