Author Topic: ATTEN F2700C / DIGITECH QT-2202, Repair / Review  (Read 5521 times)

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Offline Moshly

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ATTEN F2700C / DIGITECH QT-2202, Repair / Review
« on: July 21, 2013, 01:36:11 am »
Hi, guys & girls

I purchased a DIGITECH QT-2202 (ATTEN F2700C) frequency counter from Jaycar a few years ago.
Payed the full $200 AUD, a month later Jaycar reduced the price to $160  :palm:

I only used it a few times in a 2 year period, probably less than 8 hours in total.
Then when i need it most, no go, the display is frozen on a single digit  |O
Switching it off an on again just made it display random segments on the first digit.

After probing about, i found that the 13MHz TXCO was not oscillating.
Actually it had a temperature related fault, warm it up a bit and it starts working.

Searching Ebay i found these 26Mhz TXCO's for only $2 AUD each ->
eBay auction: #http://www.ebay.com.au/itm/TCXO-26-MHz-SMD-Toyocom-/121130161455?pt=LH_DefaultDomain_77

So after receiving a few, i made this little replacement PCB.
Firstly the TXCO is 3.3V so i need a 3.3V regulator.
Then i need a transistor buffer to give enough level to drive the 74HC74.
The 74HC74 divides the 26Mhz in half to give 13MHz.

Originally using my FE-5680A as a reference, and once the rubidium standard and the TXCO in the counter had stabilized, the counter would flip between 10,000,034Hz and 10,000,031Hz every 2 seconds.

Now, with my reference installed, it displays 10,000,000Hz or 9,999,999Hz  :-+

So, now for a quick review of the counter.
1, The push buttons are crappy, had to fix one that the little U shaped flipper spring had snapped. Replaced it with a bent paper clip  ::)
2, The 7 segment display is screwed up when displaying the 1 digit, the LEDs are lit wrong, segments E & F instead of C & B  :palm:
3, The BNC socket on the back is a 13MHz output, not a 10MHz reference input  :wtf: useless.
4, The counter is not very sensitive and easily gets confused by noisy input signals.
5, The ATTEN version is now available for around $100 USD  :(

So overall it is ok (if it doesn't fail), but i will think twice before looking at any test gear from ATTEN & Jaycar/DIGITECH again.
 

Offline saturation

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Re: ATTEN F2700C / DIGITECH QT-2202, Repair / Review
« Reply #1 on: July 21, 2013, 01:00:11 pm »
Sorry to hear; I would do the same, Atten is not in my list of preferred brands.

Consider a used Racal-Dana 1991 or similar series, and snatch it up when it appears.  It was a UK company so I presume the meters are easier to find than those of HP.


http://www.ebay.co.uk/itm/RACAL-DANA-1998-FREQUENCY-COUNTER-10Hz-1-3GHz-WITH-OPTIONS-04B-10-/151071966348?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item232c97448c
Best Wishes,

 Saturation
 

Offline Hydrawerk

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Re: ATTEN F2700C / DIGITECH QT-2202, Repair / Review
« Reply #2 on: April 28, 2016, 10:54:34 pm »
http://www.radiomuseum.org/r/hungchang_multifunction_counter_hc.html
ATTEN F2700C is probably heavily inspired by a 1980's Hung Chang frequency counter HC-F1000.
Amazing machines. https://www.youtube.com/user/denha (It is not me...)
 


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