Home |
Search |
Today's Posts |
|
#1
![]() |
|||
|
|||
![]()
On Sun, 11 Jun 2006 20:29:17 GMT, "Frank's"
wrote: They will simply represent the potentials distributed throughout an imaginary land mine field. Tap dance with care or you may have to sign off as Stumpy. 73's Richard Clark, KB7QHC Dan, The only way you will get a valid measurement is with your 1:1 transformer, coax, and your vector voltmeter. I guess if you are having problems with the vector voltmeter you can do the same, with less accuracy, using a dual channel scope, and directional coupler. 73, Frank Hi Frank, Thanx for filling in one of the gaps, what I called the mystery box. I'd forgotten Dan had been posting about his use of a vector voltmeter. Dan, this is one of your habitual problems of describing the problem at hand. You are making presumptions that all your correspondence before you has been held in suspension to consider every posting you make ever after. Always fully describe what you are doing, and why you are doing it. However, the matter of making the measurement is still problematic. Scope probes have spring-like clips used to secure them to the point or wire they are measuring. These are properly called "hoods" and in most cases are removed if you are going to probe a circuit board trace. That probe end is coaxially surrounded by a ground ring, and scope probes often came with an accessory kit that would have a special adapter that fit on this and extended a barb like a bayonet. This barb was an extension of that ground ring to find the ground point for the circuit board measurement (it presumed a ground trace was within a quarter inch or so of the measurement point). Barring this fine touch, that same accessory kit would come with two alligator leaded wires with snap attachments that would fit around the probe/cable attachment to exposed ground of the coaxial cable. Depending upon how high the frequency, or how fast the rise time of the measurement, you could use the longer, or would be forced to use the shorter lead. If you were out for accuracy, you used the barb already mentioned. This, of course, reveals the necessity of both grounding for reference, AND making it a short path so as to not make your probe part of the circuit. It hardly matters if you use a 10:1 or 100:1 probe, because if you don't use these short leads or the barb, your 2 meter antenna has probably just doubled its length in a very unpredictable manner. 73's Richard Clark, KB7QHC |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
The Shortwave Antenna used determines the type of Matching Transformer | Shortwave | |||
AM/MW Loop Antenna - Inductive Coupling -vice- Resistor Spoiler | Shortwave | |||
Grounding | Shortwave | |||
No CounterPoise - Portable Antenna System | Shortwave | |||
Outdoor Scanner antenna and eventually a reference to SW reception | Shortwave |