The stability of the Agilent and most frequency counters is dependent on the stability of the time base. They shipped with 3 different reference options depending on the order. Crystal / TCXO / HSTCXO. A lot of these have had the higher stability time bases removed because they shared the same time base as the spectrum analyses of the time. Hooking it up to an external Rb should calm it down nicely. I have done some testing in the lab and with a good stable time base in an nonideal environment under 100uHz of standard deviation can be expected.
I got very lucky on eBay several years ago and for $40.00 U.S. I bought a Systron Donner 6030 uW counter which covers 10hz to 26.5Ghz. It was cheap because error messages appeared on the display at boot-up and the seller had no idea what it actually was. All I needed to do was re-seat a few connectors and allow some time for the 10Mhz time base to stabilize and lock. The manual specifies at least 72 hours of warm up for the 10Mhz osc. It also came with the optional Amplitude module which measures from ~ -35.x dBm to +20.x dBm from .1 to 26.5Ghz which is a serious bonus...!!! 73...Jordan VE6ZT
Great video! I really enjoy the VFD displays and miss that technology! What caused the center digit to seem super bright at the 6:20 mark? It looks like they push that digit pretty hard during power up. The fan staying on could be a temp sensor gone bad. Check the manual to see how the fan is supposed to operate. I used to put 12 volt computer fans an the back of my ham radios attached to the heat sink and run them at 8 volts and you can hardly hear them run.
I am glad its not just me then. I have 10 digits in my Racal 1998, Fluke PM series and the same Agilent as yours. Strangely the Racal tends to be my first choice at the bench even though they are all GPS locked. I just like the LEDs and simple interface. Plus it is a rock solid performer. Karl
I just bought a ex-surplus Racal-Dana 1998 (2 channel measuring up to 1.3GHz) with all the options. It was pretty good standard, button all still ok and even though it has the high accuracy oscillator, I drive mine with a GPS derived 10MHz clock (Leo Bodnar GPS).
The 181A's big brother 53131's fan is always on as well, drove me nuts too. I disconnect power and I use my Rb or GPSDO standards when I need it just like you.
Other people have pointed it out too, the Racal can do 10 digits as well.. I've a couple of 1998s, bought as faulty mil surplus, they came with the 04B High Stability OCXO option and they are just excellent, 10 years out of cal when I got them. They're not lying when they say 'High Stability', compared with an Rb and a GPSDO they were less than 0.25Hz off, so close it wasn't worth breaking the cal seals.
You're chasing Allan Deviation with the 10s, 1s, and 0.1s specs being the most relevant for frequency counters. The Allan Deviation short term stability is unrelated to the long term stability/accuracy. You can have one optimized more than the other.
And poor little me. I have none. But we have to put shoes on the kids feet first. And I have to buy a new water pump for the Pinto so I can get to work. And then we have to pay the storekeeper for that sack of cornmeal and sowbelly he let us have on account.
Some get their parts from overseas, I get my parts from old tv's! I also had a 74 Pinto with an exhaust clamp holding the broken rear spring leafs together!
Yeah I've just been looking, I found 1 at £150 but had not been tested or switched on sold as 'parts not working ' ! that's too much of a gamble but there could be nothing wrong with it ! I don't buy this sort of kit with VFD displays until I've seen a picture at least.
I reworked my 53131A (which has the same always-on fan problem) to use a hard power switch, since I use an external reference. Look for a youtube video called "HP 53131A Hard Power Switch Modification" for the example I followed. Have been very happy with the results ever since I did that.
I don't know how many freq counters I have, but I know I have 2 different HP models with Nixie tubes. I would have 3, but I hurt my back trying to move my HP 524C so I left it sitting by a dumpster.
Not very far down the rabbit hole. Now you "need" an HP 5335A with the ten second gate modification - 12 digits plus exponent. Then, to test them all, you "need" an HP 5372A Frequency and Time Interval Analyzer - the microscope of counters. Looking forward to a video on the counter tests. Regards, David
I wanted to swap my power switch to on-off-on when I had my hp counter apart but forgot. It would be nice to turn the heater off. I ain’t tearing it apart again till it dies.
Think God could be a frequency? Does G.O.D stand as an acronym for something? Could the lost language between us and what ever put us here could be something ad simple as the right frequency??? Think outside the box there may be something that someone realizes. Form your own concept or build off this but think.... THOUGHT
