Spurious RF emissions?

[WRTC928]

I don't want to ask this question in an amateur radio forum because I'm afraid I couldn't get a straight answer, so I'll try it here. If I understand correctly, any "spurious emissions" will not be retransmitted by a repeater. It will pick up the strongest part of the signal and retransmit that on a different frequency. So, my question is, how much harm can spurious emissions from a 5 watt HT actually do? Yes, I understand about the possibility of creating interference in a frequency allocated to public safety or commercial radio, but realistically, how likely is that? Hams tend to think of these things from the standpoint of tall antennas and high wattage, and you likely could muck up stuff with a 50' antenna and 1,000 watts, but a 5 or even 10 watt HT doesn't seem to have much potential to cause trouble.

Do commercial LMR and public safety radios have filters to eliminate the "fuzz" created by a low-power harmonic? I assume the technology exists, and if I were building a $1,200 radio for a police department, I'd certainly include it. I'm not arguing that a "cleaner" signal isn't better and more desirable, but I suspect the "dirty" signal from a cheap HT isn't going to actually matter to anyone.

I already know @OffRoaderX's opinion  but I'm curious what the rest of you think.

[nokones]

If I recall, one of the reasons why the Television Industry wanted to migrate to digital emissions so they can be creative in using the same bandwidth of their licensed broadcast channel and cram in other broadcast channels in the same bandwidth.

[Lscott]

The issue of harmonics isn't as simple as it seems. Harmonics at the wrong frequency can mix with a wanted signal to generate a signal frequency which will appear in the radio's IF stage. This unwanted signal generation can even take place in the radio's front end amplifier stages before the mixer. That's why better radios have tunable front end filters before the RF amplifier stages. They can be adjusted on the fly to limit the bandwidth of the signal to just the range the radio is designed to receive.

https://en.wikipedia.org/wiki/Image_response

I've attached a section of a schematic for a very basic Kenwood TK-3360 16 channel analog only commercial radio. The signal path from the antenna to the first IF amp is the heavy black line. The electronically tuned band pass filter is in the red box. Many cheaper radios don't have this, particularly the CCR's. This is why many people prefer to use the more expensive commercial radios.

 

 

[nokones]

21 hours ago, wrci350 said:

The "Digital Transition and Public Safety Act of 2005" mandated that TELEVISION move from Analog to Digital, to free up space for public safety.  It did not mandate that public safety move to digital.

Either you misunderstood your friend or he is misinformed.

Federal grants for new communications systems mandate P25.  That doesn't mean a new DMR, NXDN or analog system can't be set up, it just means that system won't qualify for those grants.  There is nothing "illegal" about analog or non-P25 digital public safetey radio systems.

I believe the new encryption and radio inoperability requirements for Federally and some States funded systems may be the reason why most agencies are migrating to P25  Phase 2 Sysitems

[Lscott]

1 hour ago, nokones said:

Federally and some States funded systems

That's also why I typically see P25 radios selling for ridiculously high prices. The seller seems to think everyone is going to get a piece of the government money pie to offset the higher cost. Even used P25 radios seem to be priced at a premium.

[TerriKennedy]

On 4/7/2025 at 7:06 PM, LeoG said:

Pretty much the name of any bill is the exact opposite of what it actually will do.

Like my grammar school history teacher taught us, any country that has the words "Democratic" in its official name, isn't.

[WRYZ926]

9 hours ago, TerriKennedy said:

Like my grammar school history teacher taught us, any country that has the words "Democratic" in its official name, isn't.

Or if the name has "Peoples Republic"

I know the reason for Baofeng releasing the GT-5R was to clean up the SE on the earlier UV-5R radios. The UV-5R radios prior to the release of the GT-5R were pretty dirty. Though the front end was not improved on the GT-5R, it is still susceptible to front end overload.

I have both radios and the GT-5R does a better job overall and is clean.