Checking RD4000

[Newbie]

Hello again,
My first post is here:
http://www.thecablevine.com/forum/sh...to-get-started..

OK, I have gotten myself a used RD4000 set off ebay to learn the trade.(Arrived a few hours ago)
Put in fresh set of batteries into the transmitter and receiver and they both turn on OK.
Did a 'self test' on the receiver and it went through the routine and at the end says "Pass"
(I learn all these from the manual that I downloaded)
So far so good except for the next part:
I put the transmitter on a table(2 ft high) and from a distance of about 3m point the receiver toward the transmitter, the receiver peaks and nulls at the exact direction toward the transmitter, hence the direction is good. However when I press the 'depth' button, the depth displayed is nowhere near the correct depth.Something like 71cm when the actual distance is 3 meter and 84cm when the distance is more like 4.5m.

What I want to know is, is this just a simple case of the unit being out of calibration or something much more serious that that? Thank you for reading and any insight is very much appreciated.
What other test can I do to check out the unit before taking it outside?
TIA

[4Q2]

From what you describe, sounds like the unit is working correctly. Depth measure on most locators is only an estimated depth. This measurement can be affected by a lot of different outside factors to numerous to go into here. Using the transmitter as a target definitely will not give you an accurrate measurement, most here will not be surprized by your results. Try direct connecting to a target line of known depth. Trace line minimum 10 meters from transmitter to a place of known depth, place on surface directly above target line and check there. Should be more accurate, but will never be perfect.

[Newbie]

From what you describe, sounds like the unit is working correctly. Depth measure on most locators is only an estimated depth. This measurement can be affected by a lot of different outside factors to numerous to go into here. Using the transmitter as a target definitely will not give you an accurrate measurement, most here will not be surprized by your results. Try direct connecting to a target line of known depth. Trace line minimum 10 meters from transmitter to a place of known depth, place on surface directly above target line and check there. Should be more accurate, but will never be perfect.

Thanks, that is good to know, I'll take it outside and test it on known depth as per what you suggested.
Here is a quote from the manual on the test that I attempted:

Refer to illustration 2.
Move the receiver from left to right and when the maximum signal is obtained place the receiver on top
of a non-metallic object, such as a cardboard box, on the ground. Ensure that the blade is horizontal and
pointing towards the transmitter. To reduce the effects of ground coupling the receiver, when it is placed
on the box, must be more than half a metre/18 inches above the ground
• Press the depth/current key on the receiver
• Using a tape measure, measure the distance from the base of the receiver to the centre of the transmitter
• Compare this reading with the depth reading on the receiver.
The receiver can be considered accurate if the difference between the depth reading on the receiver and the
distance measured with the tape is less than 10%.

My next question is, I notice there is a 'calibration sticker' on the units and it says due date is 1/1/2009. So if I send these units in for calibration, what exactly got calibrated and how much should I be expecting the charge would be?
TIA

[UULC]

I see you are in Asia? Here it is about $150.00 in the States. There are several company's that calibrate both the transmitter and receiver. They really do need calibrated every year. You can check it just like 4Q2 said or send it off. With the units getting slammed around in the vehicles, they do tend to get out of wack. What they do to them I do not know. I have had all mine done after checking a known line both vertically and horizontally and found it to be off by 1.5' horizontally.

[GroundScope]

Dont worry about that method in the book, I tried the same with my RD4000 with similar incorrect result as yours.
I have some utilities here that I use to test my locators & the RD4000 is bang on in depth.

You need to find a uncongested pipe or cable that you know, dig down to get the true depth if you have to. Direct connect to the service & then practice locating it. The result should be the same using peak & null walking away from transmitter as walking toward it (using peak & null). If all indications show the same location & the depth is the same as you measured then the calibration will be correct. Try same on a few different frequencies.

[Newbie]

Thanks for all the replies.
Good news, took the unit to the neighbourhood park, the underground power line there was busted awhile back and I actually saw the actual construction work replacing the cable, they dug a 1m deep trench..Placed the unit on the 'riser' that goes up the power pole, and started tracing. The first reading, about 20m away, gave a depth of.. 106cm..next few gave about the same, 90-110 and a couple of odd ones of 76cm..peak and null at same spot etc.. so looks like I have a working unit..yay..


As per other tests, the unit that I bought does not come with accessories, hence no clamping or direct connect at the moment. Off to the ebay again for those..
Thanks again...