Repeater Offsets

[MNRotrMedic]

Hi all-i know i'm sorta asking for repeat info i would like for someone to steer me towards a website or provide info on standard repeater offsets across the bands. I understand the the UHF offset is a standard 5 megahertz above the output frequency (in: 466.000 out: 461.000). I would like similar information for VHF, 800mhz and such info please. I find it very useful for when i'm searching through the FCC database trying to ID new stuff. Thanks in advance for any replies.

Matt

 

[diskmonger]

Hi all-i know i'm sorta asking for repeat info i would like for someone to steer me towards a website or provide info on standard repeater offsets across the bands. I understand the the UHF offset is a standard 5 megahertz above the output frequency (in: 466.000 out: 461.000). I would like similar information for VHF, 800mhz and such info please. I find it very useful for when i'm searching through the FCC database trying to ID new stuff. Thanks in advance for any replies.

Matt

You're correct, the UHF stuff is generally 5Mhz above the repeater frequency. VHF on the other hand, if your speaking about public safety, could be anywhere. most of the depts in my area (michigan) all have different offsets.

 

[nd5y]

This is a general rule of thumb and doesn't count
ham radio bands and other special cases.

30 - 50 no standard offset
138 - 174 no standard offset
220 - 222 +1 MHz
406 - 420 no standard offset
450 - 470 +5 MHz
470 - 512 +3 MHz
746 - 806 +30 MHz
806 - 896 -45 MHz
896 - 940 -39 MHz

 

[MNRotrMedic]

Thanks nd5y, though i was REALLY hoping that there was a standard offset for VHFfrequencies. Although it is comforting to see that most of the inputs run higher than the outputs. That gives me a rough outline to work with.

 

[K5MAR]

Thanks nd5y, though i was REALLY hoping that there was a standard offset for VHFfrequencies. Although it is comforting to see that most of the inputs run higher than the outputs. That gives me a rough outline to work with.

Matt, the problem on VHF is that too much of it was already allocated before repeaters became economical enough to be popular. To establish a standard offset would have required the FCC to totally reallocate the VHF band, a move that (for various reasons) would make the upcoming 800 MHz rebanding look simple by comparison.

Dem's da breaks! :lol:

Mark S.

 

[nmfire10]

Although it is comforting to see that most of the inputs run higher than the outputs.

That is pure cooincidence.

 

[N_Jay]

That is pure cooincidence.

Yes, but it gives him "comfort", so don't take that away from him.

 

[SlipNutz15]

It's his "blanket" of comfort hah

 

[OpSec]

Most of the VHF systems around here are 153-155 MHz outputs with 156-159 MHz inputs...makes for some short antennas with those high inputs.

 

[Voyager]

Most of the VHF systems around here are 153-155 MHz outputs with 156-159 MHz inputs...makes for some short antennas with those high inputs.

Uhhh. the difference between 154 and 158 MHz is 0.46 inches (less than half an inch). You are not telling me you can see that on an 18" antenna, are you?

Besides, most antennas have enough bandwidth to cover the entire PS band when cut for the center (155 MHz).

Many antennas come precut, too, and cannot be trimmed without losing the ball on top.

Note: I'm talking about quarter wave antennas here.

Joe M.

 

[DaveH]

That is pure cooincidence.

I wouldn't call it that myself. The number of cases I've
seen in 450-470 that don't use positive offset are very
small (in fact I can't think of any, just odd cases that
don't use 5MHz).

I realize this question is for the US. In Canada,
the "5MHz" offset may be 5.0000 or 5.0125, or 4.9875
less commonly. There are also cases of 4MHz in the 420-430
band. There is no T band (470-512) but I'm sure +3.000
MHz is the US rule, barring odd exceptions.

Dave

 

[N_Jay]

I wouldn't call it that myself. The number of cases I've
seen in 450-470 that don't use positive offset are very
small (in fact I can't think of any, just odd cases that
don't use 5MHz).

I realize this question is for the US. In Canada,
the "5MHz" offset may be 5.0000 or 5.0125, or 4.9875
less commonly. There are also cases of 4MHz in the 420-430
band. There is no T band (470-512) but I'm sure +3.000
MHz is the US rule, barring odd exceptions.

Dave

I think the issue is that if it is a band with coordinated repeater pairs then the offset is ALWAYS according to the coordinated structure (E.G the chart)
If it is a band that is NOT set up with coordinated repeater pairs, then just because more bands have a positive offset rather than a negative offset is irrelevant to helping you find the specific offset of that repeater.

Clear?

 

[OpSec]

Uhhh. the difference between 154 and 158 MHz is 0.46 inches (less than half an inch). You are not telling me you can see that on an 18" antenna, are you?

Besides, most antennas have enough bandwidth to cover the entire PS band when cut for the center (155 MHz).

Many antennas come precut, too, and cannot be trimmed without losing the ball on top.

Note: I'm talking about quarter wave antennas here.

Joe M.

We don't use 1/4w antennas...5/8w whips that are cut too short (IMO) for 159 MHz.