SteveShannon

My wife has had maybe 40 of these (MS and they used to track the progress by scanning multiple times, with and without gadolinium enhancement) and I’ve had 3 or 4. I always wonder which of those sounds mean I need to hold my breath. You can’t hear it very well on that video, but the background sound that sounds like a fetal heartbeat is what I imagined/misunderstood you were hearing on the radio.

That’s really the important thing!

Thanks! That’s a thought. As I recall, maybe incorrectly, the characteristic sound of an MRI is from a compressor used to supercool magnet coils. I don’t know if the compressor is inside the magnetic shielding or how that all works, but maybe the VFD for the compressor is causing problems. Anyway you look at it RFI within a hospital could be bad.

Very cool, @Lscott! It would be great if the antenna manufacturers all provided EZNEC models of their antennas. I’m thinking it the DB404-B and how the folded dipoles can be rotated on their mast to accomplish exactly what you’ve illustrated.

No RF should be able to be heard through the shell. According to the article I linked, RF should be shielded to 100 dB, but according to the OP, something recognizable as RFI matching the sound of the MR scanner is being received 3/4 mile away. Just for curiosity’s sake, can you ask the gentleman if that sounds right?

Another thought. I wonder if the communication system in the MRI uses an FRS radio on that frequency and you were simply hearing it.

It should probably be reported to the MRI department. If it’s a shielding problem their techs or someone else might be exposed to too much RF. I don’t know if that’s a concern, but I notice that they go into a separate room instead of staying in the room when I have an MRI. Here’s an article on the RF shielding that’s supposed to surround an MRI machine: https://mriquestions.com/why-rf-shielding.html

The elements are light, but they’ll have a wind load normal to the strongest axis of the fiberglass mast. A 40 foot fiberglass mast at 1.75 inches will be very flexible. Even just the elements would make the mast sway in the slightest breeze.

The comprehensive data sheet refers to the included mast as a reflector: https://www.commscope.com/globalassets/digizuite/262253-p360-db404-b-comprehensiveexternal.pdf Frankly, I think it's too much antenna to put on the top of a single 40 foot fiberglass pole that's 1.75", even with a heavy wall.

Every one of us at one time or another has either asked or attempted to understand the science of antennas on handheld radios. This video, by a well known ham radio antenna manufacturer, simulates a quarter wave antenna, held at ear ? height and illustrates the gain. It’s a short video and doesn’t go nearly far enough, but it’s interesting and could be a starting point for more in-depth conversation. The simulation software Callum uses is freely available here: http://gal-ana.de/basicmm/en/#180 And here is a video tutorial for how to use the simulator program: Finally, here’s the video on small antennas:

I can understand that; I had to look at the UV9R, UV9R Pro, UV9R Plus, and UV9R Mk1 to find the one that looked like it was the same as the UV9G. The GT-3WP that @wruu653 posted appears to be the same radio as what I posted, but in a 5w version rather than 8w and for 30% lower cost. Fortunately, Amazon has easy returns. ?

The Baofeng UV9R (ham) and UV9G (GMRS) appear to meet your criteria. Both share the BL-9 battery and it looks like they both use the 328 Moto jack. https://www.amazon.com/dp/B098JGLWZ1/ref=emc_b_5_i and https://www.amazon.com/Mirkit-Waterproof-Handheld-2200mAh-Portable/dp/B082Q1VL5Y/ref=sr_1_1_sspa?crid=3TV0O3YBECTEG&keywords=baofeng+uv-9r&qid=1675951266&s=electronics&sprefix=%2Celectronics%2C630&sr=1-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFHTkdOVFNQUVdZWEcmZW5jcnlwdGVkSWQ9QTA0NTE1NjQzTTlXRVBUNjhQMlRHJmVuY3J5cHRlZEFkSWQ9QTA5NzE4NDcxVjRRSjIwTFJBSjlCJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

I have the FT-65 as well. I really like it. I have it’s little sister as well. Both can easily be opened up for GMRS.

So the two plug connector used by Baofeng is a K-1 connector, as in K for Kenwood. There are better radios than the Baofeng. I would look at Wouxun KG-UV9G and KG-UV9D or P. https://bettersaferadio.com/wouxun-kg-uv9g-pro-gmrs-two-way-radio-shtf-scanner/

Have you found anyplace(s) where it doesn't happen?

It's also important to remember that the power output will have less effect than you might expect. That's not to say it'll have no effect, otherwise we would all have 100 mw handhelds and be delighted, but the effect on range is certainly not proportional to power. Using the Free Space Path Loss calculator at Pasternak, the loss increases by 6 dB for every doubling of distance. If you're down to 15 watts, from 25 watts, you have lost 2.2 dB. https://www.pasternack.com/t-calculator-fspl.aspx?utm_campaign=Power_Combiners&keyword=&gclid=CjwKCAiArY2fBhB9EiwAWqHK6m1sMnUKdXjKlSefQDa1mTL4ALA32Cg53fVUHsRkay7AEJN_aHBRqRoCsIAQAvD_BwE

Sure - if I had a son-in-law who was a citizen of Canada, he would still be able to use my GMRS radio when he's visiting the states. Canada wouldn't have any say in the matter and the US government has no regulation prohibiting it. In fact, if my son-in-law were to come to Montana annually for skiiing or hunting and wanted to get his own US GMRS license, he could do that. It's only useful in the US, but that's all he would need. Now if he lived close to the border and used his call sign to communicate to someone in the US the Canadian government might be upset, but that's just common sense.

There are services that exist just for that sake.

All meter ranges are calibrated at two separate points with the expectation that everything in between is linear. It’s very possible, perhaps even probable, that the low points would be quite close. It’s also very possible (perhaps even probable) that the radio puts out less power than advertised. It’s a dilemma, for sure.

It is classic RFI and if it exists everywhere in the area when you are outside the vehicle and the vehicle is completely turned off (no fancy LED lights - they’re a common source) then it’s probably more than we can diagnose. That leaves two obvious choices: Contact a local ham club and ask for help tracking it down, or avoid those frequencies. Personally, I would simply avoid the frequencies.

I’ve been on both sides of this issue. This is a quote from the FCC GMRS site: But, it’s important to note that the actual regulations are phrased differently: . https://www.fcc.gov/wireless/bureau-divisions/mobility-division/general-mobile-radio-service-gmrs

A Canadian citizen* can apply for a GMRS license for use within the borders of the United States. Since location data is prohibited from being sent through a GMRS repeater, you would have no real way of knowing whether they’re in the US or across the border. *As long as they are not a representative of their government.

It’s important to note that there have been a lot of Surecom SW-102 meters reported within this forum that have really lousy accuracy. How can you be sure it’s not the meter. Measuring a cheap radio with an equally cheap meter could be an exercise in frustration. Do you have a friend with a more expensive wattmeter that can verify your results?

So scanning range is pretty wide (first picture) and the instructions for setting the Btech GMRS Pro to scan vhf or uhf are on page 32 of the manual (second picture):

No different antenna needed. It’s receive only for the vhf/uhf bands other than GMRS. At least that’s what’s advertised. I’ll see if I can find the manual, but I would expect that all you have to do is tune it from the front panel or program receive frequencies using the CPS.