Leader LDC-822 freq counter reads accurately then goes erratic.

[cleanrf]

I have a Leader LDC-822 frequency counter that I bought on ebay. It works sometimes then suddenly reads 3 MHz or so higher than my the signal from my HP-8640B sig gen. When it does this it is also kind of erratic and bouncing around. Anyone have any suggestions?

Thanks in advance.

[bob91343]

You may have an oscillation.  Does it read anything with no signal input?

[cleanrf]

No, zero only zeros.

[bob91343]

You probably should open it and do some signal tracing.  First check the power supply.

[cleanrf]

I wouldn’t know where to start. I can easily test the power supply though. Not sure how that would cause what’s happening.

[wizard69]

I wouldn’t know where to start. I can easily test the power supply though. Not sure how that would cause what’s happening.

Power supplies can cause all sort of strange behavior in digital electronics.  If I'm doing my job right, checking the power supplies is generally at the top of the list of any debug process.   Sometime it pays to check multiple times and at different points in the system.   I'd have to say that power supplies and often the caps in them, are the primary failure point in many systems.

[cleanrf]

Makes sense. I assumed caps could be bad. I will test the power supply circuit.

I wouldn’t know where to start. I can easily test the power supply though. Not sure how that would cause what’s happening.

Power supplies can cause all sort of strange behavior in digital electronics.  If I'm doing my job right, checking the power supplies is generally at the top of the list of any debug process.   Sometime it pays to check multiple times and at different points in the system.   I'd have to say that power supplies and often the caps in them, are the primary failure point in many systems.

[cleanrf]

Power supply seems to check out. I was hoping this was a common problem.

[tautech]

3 milli hertz seem accurate enough. 

[bob91343]

Yes the persistent casual and improper capitalization, among other abuses.

An engineer I respected once told me that any unit named after someone should be capitalized.  That would include Ohms, Hertz, Volts, etc.  I find it interesting that most people capitalize the H in Hertz even when there is a prefix, such as MHz.  But they seldom do it for Volts as in mV or Ohms as in MOhms.  It really can get you into trouble with Siemens; mS rather than ms (milliseconds).

[cleanrf]

I fixed the typo of mhz with MHz.

[bob91343]

Okay cleanrf but don't take it personally.  Just venting over mistakes that are all too common.

[cleanrf]

Okay cleanrf but don't take it personally.  Just venting over mistakes that are all too common.

No offense taken here, I am thick skinned and get it.

I just hope someone comes along that has had a fixed the issue I am having the frequency counter or maybe someone has a schematic. This little thing has a beautiful display and I hate to chunk it.

[BrokenYugo]

Leader will (or at least used to) email you schematics if you ask.

[4thDoctorWhoFan]

I have the Leader 823 & initially had a similar issue.  It uses a not so common sort of BNC connector on the input where it did not have the typical circular center conductor.  The center conductor was sort of a wedge shape.  Anyway, I replaced that connector because it was very dirty & oxidized and plus I wanted to put on a typical BNC connector.  Mine has been working fine since the connector change.

[cleanrf]

I have the Leader 823 & initially had a similar issue.  It uses a not so common sort of BNC connector on the input where it did not have the typical circular center conductor.  The center conductor was sort of a wedge shape.  Anyway, I replaced that connector because it was very dirty & oxidized and plus I wanted to put on a typical BNC connector.  Mine has been working fine since the connector change.

I noticed the connector was odd. It also seems like it was more reliable the signal going into the freq counter was from a stronger signal source that my sig gen can produce.

[edavid]

I just hope someone comes along that has had a fixed the issue I am having the frequency counter or maybe someone has a schematic. This little thing has a beautiful display and I hate to chunk it.

Here's the manual...