-004.430 offset?

DTLondon · Jul 19, 2016

Hey, Folks. Brand new wannabe ham here. Just picked up a cheap Baofeng to get into the hobby and find my way around.

Looking up local frequencies the other night, I noticed the local Juvenile Hall is located on 155.220, but receives on 150.790, for an offset of -004.430. I thought offset in this area was usually + or - .6? What's going on? Is this an anomaly or an intentional move to try to prevent easy interference from pranksters?

Thanks.

wyShack · Jul 19, 2016

Although the amateur radio standard offset is 0.600 Mhz the VHF Hi band for business/Public safety does not have a 'standard offset'. Only transmit where you are authorized. While the Baofeng can transmit over a wide range all frequencies it is 'authorized' for require a user or operators license. While the Baofeng is capable of transmitting on MURS and FRS frequencies -it is not type accepted for part 95 use. Attempting to talk to other entities (like the local law enforcement) is illegal.

gewecke · Jul 19, 2016

DTLondon said:
Hey, Folks. Brand new wannabe ham here. Just picked up a cheap Baofeng to get into the hobby and find my way around.

Looking up local frequencies the other night, I noticed the local Juvenile Hall is located on 155.220, but receives on 150.790, for an offset of -004.430. I thought offset in this area was usually + or - .6? What's going on? Is this an anomaly or an intentional move to try to prevent easy interference from pranksters?

Thanks.

Return it for a refund. You need a scanner. :wink: 73, n9zas

DickH · Jul 19, 2016

DTLondon said:
Hey, Folks. Brand new wannabe ham here. Just picked up a cheap Baofeng to get into the hobby and find my way around.

Looking up local frequencies the other night, I noticed the local Juvenile Hall is located on 155.220, but receives on 150.790, for an offset of -004.430. I thought offset in this area was usually + or - .6? What's going on? Is this an anomaly or an intentional move to try to prevent easy interference from pranksters?

Thanks.

The Ham band is 144-148MHz. 155.22 is in the Public Safety band and it is ILLEGAL to transmit on those freqs.

jaspence · Jul 19, 2016

If you want to use it to monitor frequencies outside the ham band, do not program TX frequency or disable the transmit if the radio/software has that choice.

DTLondon · Jul 19, 2016

Just to be clear- I'm not crazy enough to broadcast on this freq. Last thing I need is a lifetime ham ban from the FCC before I even get a license. I was just curious about the unusual offset and was wondering if there was any particular reason for it.

mirrorshades · Jul 20, 2016

Good lord, nice to see that everyone is jumping down his throat and assume he's trying to do something naughty, instead of just asking a specific question about something he thought he understood.

Anyway, based on the info for the FCC license in use:
WPMD975 (BEXAR, COUNTY OF) FCC Callsign Details

ULS License - Public Safety Pool, Conventional License - WPMD975 - BEXAR, COUNTY OF - Frequencies Summary

...it looks like you have correctly identified the input and output of their repeater. Station types FX1 and MO would be their base and mobile stations (5W maximum output), while FB2 is the repeater (25W).

Frequency assignment/coordination is handled during the licensing process. A business will normally only get one or two frequencies, instead of a "band" or several channels to use (this is different from amateur or publicly-available services like FRS/GMRS or MURS). Their radios will be programmed for transmit and receive accordingly, and it is quite likely that the users don't even know which specific frequencies they are using.

Anyway, if you are using CHIRP to program your Baofeng, you can set the duplex value to "off" to avoid unintentionally transmitting on a specific frequency. This is useful for using your radio as a scanner, so you don't accidentally hit the button if you pick it up. If you intend to listen to several different frequencies in your area, though, I will second the recommendation to get an actual scanner instead of just using the Baofeng. It is very slow and there are other features available with a purpose-built scanner that you will find useful.

SteveC0625 · Jul 20, 2016

DTLondon said:
Hey, Folks. Brand new wannabe ham here. Just picked up a cheap Baofeng to get into the hobby and find my way around.

Looking up local frequencies the other night, I noticed the local Juvenile Hall is located on 155.220, but receives on 150.790, for an offset of -004.430. I thought offset in this area was usually + or - .6? What's going on? Is this an anomaly or an intentional move to try to prevent easy interference from pranksters?

Thanks.

In VHF Part 90 frequency assignments, the frequency offset for half duplex/repeater systems is based on frequency availability in any given location. The frequencies are picked more to avoid interference to other nearby systems. All this is handled by frequency coordinators. Coordination is generally required for an application to be considered by the FCC. So there's no specific offset in the VHF spectrum of Part 90.

UHF Part 90 (70cm frequencies) is a bit different. Offsets there are generally 5.0 MHz.

As pointed out by several previous posters, the +.6 or -.6 offsets are 2M ham only.

Something you will find useful in this hobby/vocation is to be familiar with the general rules of other radio services besides Amateur Part 97. I spent most of my career working in Part 90 Land Mobile Radio Service systems but started out building VHF radios for use in Part 80 Maritime Radio Service. That job branched out into Part 90 equipment, too. The US Army trained me to operate HF radios for the military bands. My point being that when I got interested in Part 97 Amateur Radio, it was very easy to pick up on the new rules because I had a decent grounding in the other services.

KD8DVR · Jul 20, 2016

mirrorshades said:
Good lord, nice to see that everyone is jumping down his throat and assume he's trying to do something naughty, instead of just asking a specific question about something he thought he understood.

Anyway, based on the info for the FCC license in use:
WPMD975 (BEXAR, COUNTY OF) FCC Callsign Details

ULS License - Public Safety Pool, Conventional License - WPMD975 - BEXAR, COUNTY OF - Frequencies Summary

...it looks like you have correctly identified the input and output of their repeater. Station types FX1 and MO would be their base and mobile stations (5W maximum output), while FB2 is the repeater (25W).

Frequency assignment/coordination is handled during the licensing process. A business will normally only get one or two frequencies, instead of a "band" or several channels to use (this is different from amateur or publicly-available services like FRS/GMRS or MURS). Their radios will be programmed for transmit and receive accordingly, and it is quite likely that the users don't even know which specific frequencies they are using.

Anyway, if you are using CHIRP to program your Baofeng, you can set the duplex value to "off" to avoid unintentionally transmitting on a specific frequency. This is useful for using your radio as a scanner, so you don't accidentally hit the button if you pick it up. If you intend to listen to several different frequencies in your area, though, I will second the recommendation to get an actual scanner instead of just using the Baofeng. It is very slow and there are other features available with a purpose-built scanner that you will find useful.

Paranoia is justified, since you hear all the time about people jamming public safety systems. Always assume anyone who buys a transceiver, just to "receive", actually wants to transmit..legal or not. In this case, the fears were unfounded. I hope the OP has fun, once he gets licensed.

Sent from my LG-D631 using Tapatalk

gewecke · Jul 20, 2016

These days if I don't see a call sign from the person posting, and low post count when they're asking about programming any tranceiver I assume the worst. Its usually a red flag indicating illegal intentions.

73, n9zas

DTLondon · Jul 20, 2016

Thanks for all the help, guys. And don't worry about scaring me off. You'll find I'm too much of a PITA to run and hide that easy!

mirrorshades · Jul 20, 2016

KD8DVR said:
Always assume anyone who buys a transceiver, just to "receive", actually wants to transmit..legal or not.

Again, though... the $30 Baofeng comes out ahead in comparison to a $100 scanner (or even a $50 one) for someone brand new to a potentially expensive hobby. It really is a game-changer.

I have bittersweet memories of when I got my first license at age 15 and then spent over a year just staring at the piece of paper since I couldn't afford a radio. This was a time before eBay and there was no "swapmeet" activity in my area to speak of. Eventually my family saved up and bought me a $200 Radio Shack HT covering ONLY 144-148 MHz.

I think if the $30 HTs would have hit the market at the same time as the No-Code Tech license, there would have been a massive surge in new, active hams. Anyway, enough rumination for now. Sounds like OP got his questions answered, so no harm, no foul.

DickH · Jul 20, 2016

gewecke said:
These days if I don't see a call sign from the person posting, and low post count when they're asking about programming any tranceiver I assume the worst. Its usually a red flag indicating illegal intentions. 73, n9zas

Aha! The frequency detective reveals his investigative technique.

KD8DVR · Jul 21, 2016

DTLondon said:
Thanks for all the help, guys. And don't worry about scaring me off. You'll find I'm too much of a PITA to run and hide that easy!

Cool[emoji2] I like you [emoji2]

Sent from my LG-D631 using Tapatalk

KD8DVR · Jul 21, 2016

mirrorshades said:
Again, though... the $30 Baofeng comes out ahead in comparison to a $100 scanner (or even a $50 one) for someone brand new to a potentially expensive hobby. It really is a game-changer.

I have bittersweet memories of when I got my first license at age 15 and then spent over a year just staring at the piece of paper since I couldn't afford a radio. This was a time before eBay and there was no "swapmeet" activity in my area to speak of. Eventually my family saved up and bought me a $200 Radio Shack HT covering ONLY 144-148 MHz.

I think if the $30 HTs would have hit the market at the same time as the No-Code Tech license, there would have been a massive surge in new, active hams. Anyway, enough rumination for now. Sounds like OP got his questions answered, so no harm, no foul.

In some cases, true. But they scan slow, and don't have trunking or 800 or digital. Still, I can understand, some people don't need those functions. There are very inexpensive options for that; but that deviates too far from topic. I agree also, if back in the time when code was removed from the tech license, These radios were out, it would have been something else

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DTLondon · Jul 21, 2016

I'd be pretty surprised if cheap baofengs don't act as a shot-in-the-arm for Ham. I've already read many, many accounts of people in the hobby whose first radios were Baofengs. Learn the basics AND have the ability to transmit for a mere $25? For that price you'd be crazy not to try one if you're interested in Ham.

gewecke · Jul 22, 2016

DickH said:
Aha! The frequency detective reveals his investigative technique.

So sad you don't have the same instinct Dick. :wink: 73, n9zas

-004.430 offset?

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