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
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
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_77So 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
3, The BNC socket on the back is a 13MHz output, not a 10MHz reference input
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.