Jump to content
  • 0

using VHF repeater antenna with a UHF repeater



I have the possibility of using an old VHF antenna that's up high on a water tower but want to test it to see if it would work for GMRS.  Is this a definite no it won't work or do you guys with repeater/tower experience think it would be worth trying my small mobile radio at the base of the water tower to see if the SWR is crazy high?  I spoke with the 3rd party company that does comm work in this tower and he said that antenna was put up there before his time and he doesn't know what type of antenna it is.  He said I could hook my mobile radio and an SWR meter on the input side of the duplexer and test that way.  Does that make sense?  Is that possible?  Does that mean to disconnect the antenna coax on the duplexer where it says "antenna" and hook my mobile radio up there to test?

For obvious liability reasons they don't want me climbing to the top of the tower but this is the closest I've been to finding an actual good elevation site for a repeater.

Another related question.  If there are multiple antennas on the top of this water tower, and I know which hardline I'm able to tie into at the ground, how does a guy/gal test which antenna that coax is going to?  

Link to comment
Share on other sites

3 answers to this question

Recommended Posts

  • 0

Would need to know which part of the VHF band the antenna is for.  If it was for an amateur radio 2m (144-148 MHz) repeater, it probably won't work very well for GMRS, since the GMRS frequencies are not a harmonic of 2m.  If it was used for MURS, you might be able to get away with it, but performance will still suffer.  Also, I wouldn't use a radio with an inline SWR meter to do your testing.  You really don't know what you're transmitting into.  I would find someone with a quality antenna analyzer (like a RigExpert) that covers a wide range of frequencies.

You also don't know the state of the hardline, it might have a break in it.  Probably don't want to be keying a radio into a broken coax.  An antenna analyzer can also tell you the length of the coax, so you'll have a good idea if the entire length is still good.

As for knowing which antenna the hardline is going to, aside from tracing it, I don't know of a good way to test that.  More seasoned forum members might have some ideas.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Answer this question...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use and Guidelines.