I took the 360pF one and measured channel 2 input sensitivity.
MHz dBm 200 -21 1000 -29 3000 -28 4000 -25 5000 -15 6000 0
Then I added the 1000pF too, same results though. And I know now that I should have done these measurements before I started the whole thing.
Still interested to hear about the original value.
MHz | dBm |
200 | -20 |
1000 | -28 |
3000 | -27 |
4000 | -25 |
5000 | -14 |
6000 | 1 |
This my new 12.4GHz version looks to be more accurate than my old 6GHz version. With 10s gate time Avg is only 0.0015 mHz high.Here are pictures when same 10 MHz signal is connected to EXT-REF and CH1. With 10s gate time Avg is about 0.02 mHz high and with 1s gate time 0.2 mHz high.
This my new 12.4GHz version looks to be more accurate than my old 6GHz version. With 10s gate time Avg is only 0.0015 mHz high.Here are pictures when same 10 MHz signal is connected to EXT-REF and CH1. With 10s gate time Avg is about 0.02 mHz high and with 1s gate time 0.2 mHz high.
Hi EV, sorry for the late reply to this post but any chance you still have your 6GHz version to warm-up and try a similar test (same N samples with 10s gate and a similar DUT setup) so we can get a look at the results for comparison to your 12.4GHz version? Thanks, EF
Hi Electrofan
I happen to have ADEV recordings available that may answer your request.
Annexed you will find direct comparison of ADEV measurements of the FA-2, 6 GHz and 12 GHz versions. All tests are made on CH 1 with a stable 10 MHz external reference.
One set of recordings show the ADEV self test with 1 sec. gate time and the corresponding test measuring ADEV on an independent LPRO 101 Rb-standard which has been switched on and left to itself for many months.
The other set of recordings show the ADEV self test with 10 sec gate time.
It is worth noting that all the ADEV measurements of the 12 GHz version are slightly worse compared to the corresponding measurements on the 6 GHz version. I guess that this is due to the wider CH1 bandwidth of the 12 GHz FA-2 (300 MHz vs. 200 MHz).
Cheers / Jarl
...
EV - if you happen see this, what DUT and 10 MHz reference were you using? Thx
It would be nice though to have some sort of clue as to the theory of operation/circuit so we could understand its limitations or at least to satisfy our curiosity.
Reading the datasheet you get 8 digits/s for 1 Hz signals. I suppose it is a reciprocal counter with Fref between 100 - 200 MHz. User 'hgl' observed that Fin <= 0,6 Hz reduces the update rate to 10 s and at < 0,3 Hz display shows 0 Hz.
For higher input frequencies as 1 MHz linear regession promises three more digits, so 11 digits/s are possible. Because of CPLD's max. frequency of 200 MHz it could be possible to achieve >= 12 digits/s at this input frequency.
So far theory.
What am I missing? I have a FA-2 and LH windows version 6.14 beta.
I have FA1/FA2 support in the next version of Heather. Unfortunately the code is on a computer that is in a locked down building on a university campus.
I've had a BG7TBL FA2 measuring an HP 5071A cesium beam unit since September.
Tip for newbees like me:
TimeLab from KE5FX works wth the FA-2. No special configuration required.
Choose the Aquire menu: Aquire from counter in Talk-only Mode...
Choose comport
Start Measurement
(yes, kinda obvious for TimLab users)
http://www.ke5fx.com/timelab/readme.htm
Chris
... No special configuration required.
Choose the Aquire menu: Aquire from counter in Talk-only Mode...
Choose comport
Start Measurement
.
Chris