[RFI] UPDATE re: Source power pole located - but wonder which components

[vk3od at yahoo.com]

Hi Alan
I have played around a lot with ultrasonic detection. I have access to a UE systems Ultraprobe 15000 with its Dish the UWC. I also have number of homebrew ultrasonic amplifiers and dishes. I also have access to a RE M331.Ultrasonic sound has a limited propagation range that is dependent on temperature, humidity and frequency.(the laws of physics) Buying an expensive equipment like the Radar Engineers 251 or even borrowing one would not offer you much advantage over a homebrew detector like the W1TRC design that was published in QST. The MFJ5008 looks to be almost the identical circuit  to the W1TRC design that was published in QST. If you were using this equipment regularly it might make a good investment.A good unit if you can find it is the old Techsonics Sontector ultrasonic leak detectors. This is the Model with the square Midland brand panel meter on the unit in the Bird like leather case. The newer models have a different circuit and does not behave like a receiver in terms of its response. Its very peaky like it has  squelch on the detector. The older model has a nice meter response much like a receiver and you can easly screw any 40khz detector into its input. It also has good sensitivity. Email me if you want a picture of one.Since ultrasonic is essentially short range, having expensive overly sensitive equipment almost serves no purpose. In the ARRL review of the MFJ5008 they quoted a range of 200 ft, which on a true 40khz ultrasonic signal outdoors is almost impossible to achieve based in my testing using a UE systems 40khz signal generator and the UWC 18inch dish. If I cant hear it on the W1TRC, I cant hear it on any other dish size or amplifier. I even doubt that the Radar Engineers would be able to hear a weak signal that these dishes wont detect. I believe the Radar Engineers uses a 25khz(not sure)  sensor. The UE systems Ultraprobe  can vary its received frequency from 22khz to higher than 50khz with phased detectors.
The ARRL used a T model Ford arcing source which is loud as hell. I used both a T model coil, Wimshurst spark generator, and a spark plug tester to try and generator a weak signal source.(This is difficult, to try and emulate a weak signal insulator leak) Everything generates ultrasonic noise these days. After all my testing, range is subjective and depends on many variables. Ultrasonic is essentially a very short range detection device(less than 30 metres or 100 feet) for reliability. A proper true parabolic dish shape is more important than long range sensitivity.
When I have found Ultrasonic to be effective the dish is effective under 100 ft and  most of the time especially when you use a UHF receiver like the RE330  you will be within 1 or 2 poles distance of the interference. Its then a easy job to point the ultrasonic dish to ID the pole or hardware. You would very lucky if you could detect ultrasonic from long distance off, like across  several road lanes. Wind   and obstructions severely affects ultrasonic sound range.
In short dont waste too much effort on Ultrasonic devices. A homebrew W1TRC design is good enough for telling the utility " I detected ultrasonic noise near the pole" The MFJ5008 is probably good enough for this. If you going down the homebrew path it may be worth playing around with MEM's ultrasonic mics. As far parabolic dishes go. The more convenient of  my receiver dishes are the old Sony PBR330 and PBR400(30cm and 40cm) parabolic mic dishes and make  good dishes if you can find them at non auction site stupid prices. I also have a Edmund scientific true parabolic dish which in VK was a dangerous  thing because of the sun. Its a very powerful reflector. I have had numerous accidents setting things on fire with this dish until I painted it matt black to stop it acting like a solar furnace. I also tried the squirrel baffle dish which works ok, however you want to try and get a true sound parabolic shape dish. I make these comments while using a UE systems Ultraprobe 15000 with a UWC dish as a reference standard. Last time I checked this kit was about 15,000 US dollars(it belongs to the work QTH). Its far more sophisticated than the RE251 and its supposed to be the most sensitive phased detector on the market. I am not trying to  promote the company I just want to tell you that a W1TRC is good enough and has the about same detection range. Even with my 30cm parabolic mic dish I can detect anything the UE system dish will detect under 100 ft. The UE might out perform it  out at 200ft but this not a 160 CW weak signal detection competition! Is there ultrasonic noise yes or no, in my view thats how ultrasonic should be used unless you are up on the pole in a cherry picker.
UHF is far useful. The RE 330 and 331 use the range of 330 to 340mhz for the receiver. Anything from 200mhz to 440mhz works. The 330mhz range in my experience seems to good frequency range  for picking up a wide variety of noise and seems to be upper limit of many noise sources. That is not say things like arcing sources cant go higher.  The RE331 has very good pulse detection and a AGC that responds very well to sparking pulse like noise. In contrast many receivers will smear or average this sparking noise out because of AGC or peak detector response. The RE330 is a tool that does its job well. However ordinary UHF AM receivers will get you there. I leave my receiver tuned to 406mhz which is the international 406 EPIRB satellite frequency, its reserved globally  and its close to  performance in terms of detecting sparking noise like the 330mhz range while not being too high like 440mhz where you may hear nothing. It amazes me how much RFI you hear up on 330mhz that is being emitted by modern trucks, buses, LED road signs, hazard flasher beacons, roadside LED generator lighting sets  etc etc. 144mhz pickups all this stuff from a long distance away and the 330mhz will tell you if you are close by, which in essence is the secret of RFI location, localising and getting as close to the source as possible.
Getting any information on the Radar Engineering products is just about impossible from my experience. Finding manuals is also just about impossible. The other thing to be aware of is many of there HF receivers like the 242 and 243 tune in 12.5khz steps, so many sources of interference cant be tuned in since the noise is on frequencies between the tuning steps. This comment also applies to some VHF/UHF HT ham radios that dont have 1 khz tuning steps which can be useful for tuning in switch-mode led power line birdies and hash peaks. It does not matter for arcing sources since its broadband in nature.I have wasted a lot of time hunting qrm and messing around with different types of equipment to find an effective solution which is as cheap as possible. I was just fortunate enough to have access to very good equipment to realise what is possible.  Results can be achieved with ham methods and ham budgets. Extremely high price tags do not always mean best performance, thats life!73Craig"""""*INTERESTING ASIDES*:


   - Ultrasonic dish.  I mentioned that a previous attempt with an
   ultrasonic dish some years back had been disappointing.  He said this was a
   new version (Radar Engineers) dish.



   - And, that the upgraded version had been recommended by a contractor
   the utility had recently used to survey their powerline.



   - The survey had been prompted by a series of "pole fires" they had
   experienced.



   - He described the survey as having been done from a vehicle driving
   beneath 200 miles of their lines. (1/5 of the utility's total). And, that
   the contractor had then used this latest model R.E. dish to zero in on the
   source.  Future surveying depends upon budget considerations.


*I'M CURIOUS*:

   - Is there some new technology being used for surveying lines?  I sort
   of recall reading something like this. Drones? SDR recording?
   - Or, maybe this is just some guy driving around with his AM radio on?
   - Is there a new version of the ultrasonic dish that is better than the
   previous Radar Engineers model?
   - What is the difference between RE models and the MFJ-5008?
   https://mfjenterprises.com/products/mfj-5008

I will further update when these tickets are closed out - and the defective
component is positively identified.

73, ~ Alan K0AV
Colorado Springs """