Avoiding FRS channels

[KAF6045]

2 hours ago, Blaise said:

That's actually amazing.  I've been wondering all morning how I'd explain to my wife why I was buying a bunch more test equipment to do the same thing!

I want to try it across city and inside buildings, too...

"... city ... buildings..."

Well, save your money on the field-strength meter then. The lower-cost options (<$125) are just relative field strength (consider -- they have an adjustable "sensitivity" control and just a uA meterfor display; heck the MFJ-801 even requires one to be touching the ground screw with one's hand -- so depending upon one's skin conductivity the reading may differ! The 802 is a balanced dipole antenna so takes out the human factor -- intended for 100kHz to 500MHz [so HF to lower UHF].). They are also very wide-band detectors and will register /any/ RF -- especially that joker so proud of his 60s Mustang that he won't put suppression spark plug cables on it!

In the $150-250 range one finds things being sold for health/safety checking, optimized for cell-phone frequencies, covering 50MHz-3.5GHz (6m, FM broadcast, TV, and microwaves). In the $300 range one finds units that span 10MHz-8GHz, which at least makes it useful for the upper HF bands (30m and up, but not the 40m band). Both of these ranges, however, have actual units attached to the measurement (in 7 choices).

 

As for the sending unit in these tests -- don't compound matters by using two different models to do the 2W/5W (or whatever pair)... Use one radio that is selectable for power level (high/low) and use one radio for reception (I'm tempted to suggest also using a field sound recorder with a cable from receiver speaker out to recorder aux in, and with AGC turned OFF to provide raw [WAV file] evidence that can be examined in audio editing software [peak, average, etc.])

Unfortunately, none of these meters are tunable -- so your across-town test is going to measuring any cell-phone towers, broadcast radio/TV, WiFi systems, etc.

To avoid all those would require a radar/radio test range -- and at that stage, you are back to unobstructed horizon distance and line-of-sight.

[marcspaz]

2 hours ago, Blaise said:

That's actually amazing.  I've been wondering all morning how I'd explain to my wife why I was buying a bunch more test equipment to do the same thing!

I want to try it across city and inside buildings, too...

 

That would be pretty cool to see, too. I have an MFJ-802BX. The manual says I have to be at least 10 feet away with the sensitivity all the way down, to start, but I have no idea how far away I can get.  It should be plenty sensitive enough for what we want to test, though. 

2 hours ago, Blaise said:

Yes, I was teasing just to make the point that you *don't* take your discussion to emotional hysteria, like we see so often in say this thread (and so many others)...

 

My wife always tells me I'm way too serious. I initially missed the satire... but I definitely appreciate it! LOL

[Lscott]

2 hours ago, Blaise said:

That's actually amazing.  I've been wondering all morning how I'd explain to my wife why I was buying a bunch more test equipment to do the same thing!

I want to try it across city and inside buildings, too...

You might not need to do that. There are a few select radios that include a field strength measurement feature right in the radio. I'm not talking about the crappy bar graph display either.

On some of my radios there is a "maintenance" menu where it will show the RX signal strength in dbm.

[PartsMan]

On 4/11/2023 at 6:52 PM, KAF6045 said:

The difference in range between 2W and 5W is minuscule.

For the same quality radio sure.

A cheap bubble pack with a stubby fixed antenna vs

a decent GMRS radio and antenna is a big difference.

Get a mile away and they are gone.

[PartsMan]

I do think it is crappy of the FCC to let FRS on all 22 channels.

They should have some of there own, us have some of our own, and a few overlapping.

[Radioguy7268]

I think the real world difference between 2 watts and 5 watts comes down to noise floor. Outdoors in a quiet RF space, you probably would not see much difference. In a crowded urban area with tons of RF, the 5 watts will give you the tallest weed in a field of noisy grass. The 2 watts will still be down in the grass.

 

[marcspaz]

1 hour ago, Radioguy7268 said:

I think the real world difference between 2 watts and 5 watts comes down to noise floor. Outdoors in a quiet RF space, you probably would not see much difference. In a crowded urban area with tons of RF, the 5 watts will give you the tallest weed in a field of noisy grass. The 2 watts will still be down in the grass.

 

 

That is a distinct possibility. I have experienced that on VHF. I was talking to a buddy of mine on 147.525 while I was driving out on a country road. He started to drive through a busy commercial area with tons of neon and florescent lighting, as well as high voltage lines and every other type of noise you can think of in a busy city at night. He said my signal dropped out due to RFI. I could hear him perfectly, though. I bumped my power from 50w to 200w and he could hear me, but it was still tough. With him at 50w, he was full quiet on my end.

 

I haven't really played with UHF in an urban area beyond local crossband repeat, but I have to assume it would be similar. 

[WRUU653]

Negligible - adjective, so small or unimportant as to be not worth considering; insignificant.

5 watts over 2???  After much consideration and all science aside “negligible” by definition it is not for me. Not quite insignificant enough as to not be worth considering.  Can I tell the difference?  I don’t know.  Given the option… after consideration hand me the 5 watt radio.  I mean that’s why they sell them right?  “Sir would you like the double burger with extra cheese? Yes please.” This is just my opinion, not based on any real world science or testing and may not be the views of others expressed in this ever growing thread.  Your mileage may vary. Void were prohibited. Ask your doctor if five watts is right for you.

 

[KAF6045]

5 hours ago, PartsMan said:

I do think it is crappy of the FCC to let FRS on all 22 channels.

They should have some of there own, us have some of our own, and a few overlapping.

They used to -- just look at the legal usage for the pre-2017 "FRS/GMRS" bubble pack radios. Problem was, 99% of the buyers never bothered to read the license-required to use channels x/y/z. Basically, pre-2017, FRS was only allowed 0.5W ERP with fixed antenna on (what are now) channels 8-14 and originally 0.5W on channels 1-7. (Oh, and 12.5kHz bandwidth).

So the FCC just redefined those bubble pack radios based on common features: 2W or less maximum power, fixed antenna, no repeater capability is now FRS. >2W and/or repeater capability is GMRS. I have two sets of those ancient bubble-packs: one set has H/M/L power levels (where M is the 2W setting), the other set has repeater capability. Both sets are thereby deemed GMRS rigs per the current regulations.

[marcspaz]

18 minutes ago, WRUU653 said:

Negligible - adjective, so small or unimportant as to be not worth considering; insignificant.

 

I agree on the definition.

 

18 minutes ago, WRUU653 said:

5 watts over 2???  After much consideration and all science aside “negligible” by definition it is not for me. Not quite insignificant enough as to not be worth considering.  Can I tell the difference?  I don’t know.  Given the option… after consideration hand me the 5 watt radio.  I mean that’s why they sell them right?  “Sir would you like the double burger with extra cheese? Yes please.” This is just my opinion, not based on any real world science or testing and may not be the views of others expressed in this ever growing thread.

 

I have to say... I am a power junky.  So, I will always take more power.  It just seems like a no-brainer.  I have a 1,000w amp at the house for a reason. 

 

18 minutes ago, WRUU653 said:

Your mileage may vary. Void were prohibited. Ask your doctor if five watts is right for you.

^^^  This is fantastic!

[WRUU653]

29 minutes ago, marcspaz said:

have to say... I am a power junky.  So, I will always take more power.  It just seems like a no-brainer.  I have a 1,000w amp at the house for a reason

I did notice that you mentioned you had an 8 watt radio while out with others that had 5 so I thought that might be the case  

[KAF6045]

12 hours ago, marcspaz said:

I have to say... I am a power junky.  So, I will always take more power.  It just seems like a no-brainer.  I have a 1,000w amp at the house for a reason.

WHAT! You're giving up 500W?

[PRadio]

23 hours ago, marcspaz said:

 

Oh, I'm not fighting, just having a discussion. Thats probably why it looks like I'm bad at fighting. LoL

 

I'm not disputing your technical point that more power equals more penetration or improved range. That is just matter of fact. My contention is more a matter of the significance of the improvement. 

 

That said, just to be friendly and see if you are correct or not, I am 100% willing to go in the woods behind my house with a radio and a field strength metere to conduct an actual measured test of the situation you are describing. Now, if you just want to have an exercise in rhetoric rather than discover usable and actionable information, then I'm not goto do the test. 

 

@everyone... if anyone wants me to do the test, I will, but I have no interest in doing it for my own sake. So, if anyone wants it, just let me know.

Not gonna lie, it would be interesting to see the results. I too believe they would be insignificant in a real world situation, but it would be interesting to see what the meter says, coupled with a subjective review of actual voice reception. 

[marcspaz]

4 hours ago, KAF6045 said:

WHAT! You're giving up 500W?

 

I can't afford to run 220-240 to my shack. Maybe some day.

[marcspaz]

2 hours ago, PRadio said:

Not gonna lie, it would be interesting to see the results. I too believe they would be insignificant in a real world situation, but it would be interesting to see what the meter says, coupled with a subjective review of actual voice reception. 

 

I was going to do the test today, but it's raining. Have to see if I can do it tomorrow. 

[Lscott]

I mentioned in a previous post some commercial radios have a signal strength measurement feature, RSSI, built into them. This is NOT the simple bar graph display you commonly see. 

https://forums.mygmrs.com/gallery/image/302-nx-1300duk5-rssi-display/?context=new

A number of radios have the ability to measure the RX signal strength during normal operation, typically for trunking systems with multiple TX sites. The radio can be programmed to use the site with the strongest signal.

[KAF6045]

On 4/15/2023 at 2:58 PM, marcspaz said:

I was going to do the test today, but it's raining. Have to see if I can do it tomorrow. 

A dangerous thread... I dumped near $300 for...

Measures "E (electric) field strength" (m)V/m directly ((m) in parens at it appears to autorange between mV and V) with options for (default) instantaneous (which seems unusable due to varying signals in my home), MAX instantaneous, running average, Max average. Memory for 200 measurements. Sensor can be set to use all three (X/Y/Z) elements or any single element. Tripod socket on bottom

Other measurements are computed "using the far-field equations" with far-field described as three wavelengths -- going to make 10MHz (if I ever desire to go that low) fun, as three wavelengths is 90m (295ft -- essentially a football field! That's going to be a long PTT cable ). GMRS shouldn't be a too problematic -- only 6ft: put unit on tripod, set for MAX, walk to HT, PTT for a few seconds to ensure measurement is captured. MURS would be an exercise (20ft separation).

"H (magnetic) field" (u)A/m, "S (power density)" in (m)W/m^2 or (u)W/cm^2 [not sure if the m/u unit is fixed or auto range). Warns that H field can not be computed in near-field (I suspect it can compute /a/ value, but not accurately). If power-density makes use of H field, it too would be uncertain at < 3 wavelength.

Interestingly: the manual says the 9V adapter is optional, and the calibration certificate listed "included accessories" as TWO 9V batteries. It arrived with one 9V alkaline, and (as shown) the 9V adapter. Wonder how much background RF that switching adapter is putting out

[marcspaz]

@KAF6045  That looks awesome!  If you plan to use it soon, can you let me know how you like it?

 

I took my MFJ out this morning (rain finally stopped for a couple of days) and the needle is stuck.  It was only $100, so it's not worth it for me to send it in to repair.  I was going to buy another one, but for $300, that looks like a much better meter.  If you think it's good, I would definitely get one.

 

I was looking at another MFJ or EXTECH, TENMARS, and a couple of others, including the LATNEX HF-B8G.  The only one I have seen that I can afford that I have knowledge of is the MFJ.  I don't know anyone else using anything except a newer Bird that I definitely can't afford.  Some feedback from you on the LATNEX would be awesome.

[KAF6045]

1 hour ago, marcspaz said:

I took my MFJ out this morning (rain finally stopped for a couple of days) and the needle is stuck.  It was only $100, so it's not worth it for me to send it in to repair.  I was going to buy another one, but for $300, that looks like a much better meter.  If you think it's good, I would definitely get one.

I'd rounded up -- On Amazon, the HF-B8G 10MHz-8GHz model is $272. They have an HF-B3G 50MHz-3.5GHz variation for $165 (half the weight, and if one trusts the posted specs, 5x battery life). I went with the big unit to get coverage of 20-10m HF bands (the manual seems to consider anything "high frequency", where we'd use VHF/UHF/SHF/microwave).

1 hour ago, marcspaz said:

I was looking at another MFJ or EXTECH, TENMARS, and a couple of others, including the LATNEX HF-B8G.  The only one I have seen that I can afford that I have knowledge of is the MFJ.  I don't know anyone else using anything except a newer Bird that I definitely can't afford.  Some feedback from you on the LATNEX would be awesome.

I suspect the LATNEX and TENMARS units are really the same manufacturer. TENMARS seems a bit cheaper on Amazon ($110 50MHz-3.5GHz, $253 10MHz-8GHz). The Extech cost a fortune, but appear (from posted specs) to cover a wider range (20mV/m-108V/m) -- but would you really want to be standing near an E-field reaching 108V/m! LATNEX range is 50mV/m-11V/m.

Can't trust the specifications for the LATNEX shown on Amazon -- states max display of 3999, but the images show 19999.

Somewhere I have the MFJ but I think one of the dipole whips cracked off at the base, and you can't really solder that shiny metal. Went with one of these designs as they give an absolute reading, not relative reading dependent upon a potentiometer setting.

 

 

ADDENDUM: as mentioned, my quick familiarization run found the instantaneous display unusable. Maybe it would stabilize if I: set cell phone to airplane mode, unplugged my network router, powered down the Pi-Star, unplugged the TV, DirectTV box, Blu-Ray, and maybe the Wii-U (forgot if it has WiFi capability) -- otherwise I've got all these devices making pings at unknown intervals.

[Adamdaj]

On 4/14/2023 at 4:41 PM, PartsMan said:

I do think it is crappy of the FCC to let FRS on all 22 channels.

They should have some of their own, us have some of our own, and a few overlapping.

I hear what you're saying. The majority of them bubble pack radios do cause headaches for a lot of repeaters owners and trustees, especially when you families that use them to keep track of their children. Then there's the kid playing with them and not thinking about what doing. And they don't understand that their conversation is being heard by everyone on that channel.

[wrci350]

3 hours ago, Adamdaj said:

I hear what you're saying. The majority of them bubble pack radios do cause headaches for a lot of repeaters owners and trustees, especially when you families that use them to keep track of their children. Then there's the kid playing with them and not thinking about what doing. And they don't understand that their conversation is being heard by everyone on that channel.

Well, like it or not, FRS users have just as much right to those 22 channels as GMRS users.  Unless the FCC can go back in time and not ever allow those FRS/GMRS bubblepack radios, we're stuck with sharing.

As far as repeaters go, if you run with both transmit and receive tones on a repeater you'll never hear someone using an FRS radio unless they happen to pick the same tone as what you are using on the output, correct?

You are right about the "everyone can hear you" part, and it's not just kids who don't understand that.

[Sshannon]

4 hours ago, Adamdaj said:

I hear what you're saying. The majority of them bubble pack radios do cause headaches for a lot of repeaters owners and trustees, especially when you families that use them to keep track of their children. Then there's the kid playing with them and not thinking about what doing. And they don't understand that their conversation is being heard by everyone on that channel.

How do they cause problems for repeater owners?  FRS radios are blocked from transmitting on the 467 main channels that are the repeater inputs. 

[Adamdaj]

8 minutes ago, Sshannon said:

How do they cause problems for repeater owners?  FRS radios are blocked from transmitting on the 467 main channels that are the repeater inputs. 

GOOD POINT! Yep, I put my foot in my mouth again. I apologize

[Lscott]

22 minutes ago, Sshannon said:

How do they cause problems for repeater owners?  FRS radios are blocked from transmitting on the 467 main channels that are the repeater inputs. 

 By transmitting on the repeater output frequencies. If they’re near by your location they can jam the frequency.

[wayoverthere]

27 minutes ago, Sshannon said:

How do they cause problems for repeater owners?  FRS radios are blocked from transmitting on the 467 main channels that are the repeater inputs. 

Legit radios, yes.

Joe schmoe that bought a baofeng from Amazon and programmed the FRS frequencies, and transmitting on the 467 interstitials, without realizing they needed to set it to narrowband (so instead it's bleeding into the repeater inputs on either side) could definitely be an issue.