BG7TBL FA1 and FA2 frequency analyzers

[Ringmodulator]

... No special configuration required.

Choose the Aquire menu: Aquire from counter in Talk-only Mode...
Choose comport
Start Measurement
.
Chris

Any idea why this doesn´t work for me?

hterm is working.

I see :
F-CH1:0024999999.999956054
F-CH1:0024999999.999980506
F-CH1:0024999999.999990234
in the monitor.

Line Terminator 10 or 13 makes no difference, What am I missing?

Hardware is the 12Ghz version saying 20200705 at startup.

Timelab shows only: Initializing acquisition on the right side , but not Acquired etc shown.

I am the only one?

Hi,

my unit is the 6GHz unit and the output strings have a different format.

I think, there is a possibility to taylor the input strings in timelab. I have not used this myself, so I leave the explanation up to users with better insight.

Chris

[DM4DS]

Nobody with the 12G version?

[Jarl]

Hi

I have checked with my 2019 12 24 version of the 12 GHz counter.  It has the same output format as the 6 GHz version, each line starting with
F: followed by the frequency readout in Hz.

When using TimeLab to measure frequency ADEV  I get a display as shown below. Please note the content of the various check-boxes.

It seems that BG7BTL has changed the format of the serial output in the new version. It would be of interest to know the reason for this change and to know if other features has been changed as well.

Cheers
Jarl

[rfclown]

Just received a FA-2 from eBay today. Have only measured 10 MHz so far. Ref Output was 0.11 Hz off compared to a Rubidium. So far so good. Tweeked pot to make it 0.01 Hz.

Found this forum thread and read through it. Nice to get the manual with serial commands. From what I read on the forum, I decided to measure input impedance. I haven't opened up my unit yet to see what CH2 in looks like. Calibrated to 3.5mm, so CH2 measurement is S11 at connector. For CH1, I put in a BNC to SMA adapter and didn't bother correcting for the offset since this is for lower frequencies. CH1 looks good below 500 MHz. CH2 doesn't look 50 ohms anywhere. I attached the touchstone files with .txt extension. Attached graph of return loss.

At some point I'll be doing a mod on the CH2 input.

[rfclown]

The FA-2 manual doesn’t specify any accuracy, only “resolution” (10s: 0.00001Hz@10MHz). I wanted to figure what I would consider as the accuracy for the CH1 input at 10S gate time. I connected a coax from 10 MHz REF OUTPUT to CH1. Set GATE=10S and IMP=50 ohms. Ran for one hour reading the serial port. Plotted the error (Reading-10MHz). The stated resolution is 1e-5. In the one hour run, the error for seven of 350 readings was greater than the “resolution”. For whatever reason, when reading from serial, the resolution is 1e-9. The LCD display resolution is 1e-5. I’m showing the error of the serial read resolution on the plot. I don’t know why they spew out so many digits when they are meaningless. Anyway, for my purposes based on this data, for a 10S gate time on CH1, I’m going to round to 1e-4. That gives me a 12 digit counter that’s dead on for $130. I bought this on eBay from a US seller so I wouldn’t have to wait. I tweaked the Ref pot on this (and my two Rubidiums) the other day based on a GPSDO that I finally got from China. For years I’ve been using an HP5386A that I got from eBay. The internal reference is crap, so I got some eBay LPRO 101s for a good deal, and I only use the HP if I have a rubidium for a reference. I just turned on my scope to see how close the FA-2 ref is to my GPSDO. I’m too impatient to wait for the result; it’s been 20 minutes, and it hasn’t slipped a half cycle yet. That’s better than 5e-11. I’m very happy with this FA-2. No need to fire up a rubidium to make a pretty decent frequency measurement. Some day I’m going to open it up and match the CH2 to 50 ohms.

[FransW]

You will need to contact NIST for accuracy.
Resolution is all you have now.
Further calibration to define accuray is (in my opinion) senseless or at least a waste of time.
Regards,
Frans

[tstp]

I also found that my 2020 version FA-2 does not work in either Lady Heather or TimeLab.
After reading reply #227 from Jarl, I realized that the change of frequency output format of FA-2 seems to be the cause of problem.

Trying my FA-2, I found that by changing just one setting, TimeLab 1.51 is able to read the new version FA-2:

Please fill in 3 instead of 1(default) in "Numeric Field #" within the [Acquire from counter in talk only mode] dialog box.

Then, it looks working fine now.

TimeLab is amazing and so flexible to configure! 
Reading the description in TimeLab dialog box, the explanation is:
The 3rd numeric field is just what we want, because the output e.g. F-CH1:0009999999.999912345 could be parsed to 3 possible numbers: "-", "1", and  "0009999999.999912345".


I still do not find a way to let 2020 version FA-2 work in Lady Heather which is powerful and can be used on non-PC platforms like Raspberry Pi .


Picture of output of FA-2 2020 version and the test of OCXO are attached below:  (gate time 1sec, the meaning of "*" sometimes appears before F-CHn is unknown) 

[FriedLogic]

  The FA-2 only uses measurements which are close to the previous one for calculating stats, and if they are more than a certain amount off it marks that measurement in the USB output with an asterisk. I don't remember exactly how large the difference needed to be, but IIRC it was something like a few PPM.

  Whether or not it's within this range also appears to change the dead time by a small amount. The dead time varies a little anyway, and also changes with the mode.

  The actual gate time on the one that I tested appears to be 10.24s on the 10s range, and then about 100-140ms dead time. I'll need to write up the tests that I did sometime...

[elwood]

Hi all,
got my FA-2 yesterday and see the problem. Connected the cable to the reference generator 10 MHz on the back and constantly blinks the difference of 1000 Hz. When the "star" on the top right shines, it shows the real value, but when the "P" appears, it shows less at 1000 Hz. What could be the problem? Unfortunately it is difficult for my understanding.

[rfclown]

I don't see such behavior on my unit. In 0.1S gate time I get about 0.002 Hz P-P. In 1S gate time I get 0.0002. I don't use 0.1S gate time much at all. My suggestions:

1. While in the statics mode (like shown in your picture), push the RST buttom to reset the stats. It could be that you plugged the cable in while stats had already started.

2. Use longer gate time (1S or 10S).

Someone posted an English version of the manual which explains the * and P. The * flashes with the gate. The P is high precision mode.

[elwood]

2. Use longer gate time (1S or 10S).

All modes have been tested. Time does not affect anything. The developer admitted that a chip on the board is faulty.

[elwood]

Hi all,

Today, just in case, I opened the frequency meter, took a photo, looked closely at the board and noticed a couple of solder hairs in the wrong places (near the sop-8 chips), cleaned and washed the board with alcohol. Now everything works fine, "P" mode is always on 

[Ringmodulator]

On eBay a new version of the FA-2 showed up, the FA-2-6G PLUS.
It has 6 pushbottons and displays 2021 01 31 as version (date).

[mankan]

There is also a 12G PLUS and a 26.5G PLUS. However, still no sensitivity spec over 10GHz.

[MegaVolt]

FA-3

https://www.ebay.com/itm/124669140586

[mankan]

Looks like larger screen and other button layout, also available here in multiple variants: https://www.aliexpress.com/item/1005002477751627.html

[Ringmodulator]

The 3.2"display is a really nice upgrade!

[Diabolo]

The 3.2"display is a really nice upgrade!

Hello,

The screen 3.2 is bigger, but the slab is placed behind the front facade and it is not pretty, it would be necessary to install a plexiglass plate perfectly adjusted in the window cutout.

Regards

[rfclown]

I just discovered something about my FA-2. The CH2 input needs about 0 dBm at 1-3 GHz to give proper readings (I've not characterized this at other frequency ranges). The unfortunate thing is, with a lower level (like -10 dBm) it gives a reading (in the ballbark), but incorrect. Took me a while to figure out why my measurements were off. When I first got this thing, I was mostly using the CH1 input for 10 MHz signals. I've been very pleased with the price/performance ratio of my FA-2. Since there are so many versions of this thing, it's impossible to know what the "specs" really are. That's part of what I have to put up with in buying a cheap instrument.

[Grandchuck]

I just checked my FA-2 at 1.5 GHz.  It works down to -29 dBm.

[Kosmic]

I just checked my FA-2 at 1.5 GHz.  It works down to -29 dBm.

Got similar results over here. At 1.5GHz the minimum is -27dBm, 2.0GHz it's -30dBm and 2.7GHz around -34dBm.

Specs of channel 2 from the manual:

CH2 Frequency range: 30MHz-6GHz
CH2 Input impedance: 50 OHM
CH2 Frequency resolution：0.1s: 1Hz@1GHz
 1s: 0.01Hz@1GHz
 10s: 0.001Hz@1GHz
CH2 Input power range:-20dBm- +13dBm@0.5-5GHz,
CH2 Connector type: SMA

you should at least get -20dBm on channel 2. If not, the prescaler is probably damaged.

[rfclown]

I just checked my FA-2 at 1.5 GHz.  It works down to -29 dBm.

Got similar results over here. At 1.5GHz the minimum is -27dBm, 2.0GHz it's -30dBm and 2.7GHz around -34dBm.

Specs of channel 2 from the manual:

CH2 Frequency range: 30MHz-6GHz
CH2 Input impedance: 50 OHM
CH2 Frequency resolution：0.1s: 1Hz@1GHz
 1s: 0.01Hz@1GHz
 10s: 0.001Hz@1GHz
CH2 Input power range:-20dBm- +13dBm@0.5-5GHz,
CH2 Connector type: SMA

you should at least get -20dBm on channel 2. If not, the prescaler is probably damaged.

Thanks for the responses. I guess it's my unit. I don't believe I've ever put a large signal in CH2.

When I had a smaller signal, the reading wasn't way off. The only reason I noticed is because I had both the FA-2 and the transmitter I was measuring using the same 10 MHz reference from a GPSDO, so I knew it should be spot on.

Edit: I must have been doing something wrong. I just double checked with a signal generator, and it's more like -21 dBm at 1G. I must have been mistaken as to the level coming out of the source I was measuring previously.

[burkm]

As the 1st few reviews of the FA3 are coming in it seems - at least to me - that the FA3 is just a FA2 with a somewhat larger display and casing. All the other "ingredients" including the prescaler of the F3 version and the stated specifications seem to be identical to the FA2 version. The elevated prices for the F3 version asked for right now on several market places (ebay, aliexpress etc.) therefore are quite overpriced because of this - from my point of view - probably because of a lack of reviews and detailed information on these units. I would wait awhile whilst the pricing will be approaching more realistic levels...

[Ringmodulator]

I have both, the FA-2 and FA-3.

I had a short look inside the FA-3 and it looks like it has the board of the FA-2.
(I did not compare them side by side)

Removing the protecitve foil on the display was a real pita and required disassembly to remove the display.

The front panel has 2 additional buttons, but they are for the impedance and the LPF, which can be switched
 on the FA-2 by pressing 2 buttons. So no additional function or features here.

According my tests, the performance is identical.

So, ift it is not for the bigger display, I suggest to go with the FA-2.

Chris

[burkm]

If the bigger display is the real difference between those two I would go for the bigger display (F3) but not at those prices asked right now...