Any Ham Radio wizards here.?

Hi,
Just got a scanner. All programmed ok.
However I notice that when I hear one party transmit on channel 71 - I never hear the receiving party respond. I know they have cos the original party acknowledges the contents of the return message - which I never hear. Is it something to do with VHF line of sight - or something else. ?
Guidance/help appreciated. tks.

geek_south9, May 18, 2:38 pm

What is channel 71?

geek_ians2, May 18, 3:49 pm

Sorry - its a local Maritime station used by Wellington Harbour radio.

geek_south9, May 18, 3:55 pm

Most likely a repeater site. Where signal is transmitted on one frequency and received on another. Don't know how your scanner works but sounds like it is locked onto one freq.

geek_fertman, May 18, 4:09 pm

71 isn't a repeater.
You'll just be hearing one side of the conversation because the other side is out of range for you.

You probably need a better aerial, although you might just be in a bad location for the other persons location.

The frequencies are here.
http://www.offshoreblue.com/communications/vhf-nz.php
For the repeater frequencies, you would need to listen to the "ship receive" frequency.

geek_johotech, May 18, 4:14 pm

Tks for that johotech.
If you can picture a triangle- I'm at one point and can see the other two.
I can hear one point transmit to another - both of them in visual sight to me,
but i only get one side of the conversation. ?
Will have a look at the www you refer to and see if that throws any light
on the problem.

geek_south9, May 18, 4:26 pm

Maybe you aren't listening to channel 71 then. I would have thought you would have only known the frequency from your scanner, not that it was channel 71? How did you figure that out?

geek_johotech, May 18, 4:33 pm



Nor is it Wellington Harbour radio.
It's a Maritime NZ working channel.

As you've described it - with two boats visible which are equidistant to you - but you can only hear one, perhaps one has their VHF turned to 25 watts and using a decent VHF antenna, perhaps the other is using a small handheld on minimum power - 0.5 watt or whatever.
You might be able to hear the one with the poor signal if you adjust squelch - or toggle off auto squelch etc.
If the two boats communicating with each other are within line of sight, then they should switch to Ch 6 or 8 rather than clog up the (monitored) MNZ channel.
If they're talking to MNZ, then MNZ probably has a massively powerful VHF and good well-positioned antenna.

geek_mm12345, May 18, 4:36 pm

This may be of be of help.
Years ago I was asked to sink a well casing to 73 feet depth.
The owner then tuned it to suit as a Ariel, by cutting it down a bit at each time, seems that being in the earth gave a good range.
Owner was a ham radio operator here in CHCH,
Has any one knowledge of this being done.

geek_aj.2., May 18, 4:45 pm

Tks guys- appreciated
I know its channel 71 because i hear the transmitting station (below) say "Go 71"
I can pick up the MNZ weather transmission ok ( they are at Taupo aren't they? ) and I can hear the Wellington Maritime Radio(Beacon Hill) say "Go 71" but I just can't hear the reply. The scanner shows 156.570. I have an aerial mounted on roof which is in line of sight to Beacon Hill and covers well out into Cook strait.

geek_south9, May 18, 4:49 pm

aj.2. Sorry no go here - two inches below lawn here is solid rock. )))))

geek_south9, May 18, 4:52 pm

Should be 156.575Mhz
Would make a difference with the weaker signal.

geek_johotech, May 18, 4:58 pm



Saying that - "Go 71" - wouldn't be something said by someone already on Ch71. More normally an instruction by MNZ on Ch 16 for the boat to go to Ch71 as it's the local working channel. There may not be a response, though etiquette may be for the vessel to respond that they're going to Ch71 and "clear" on Ch 16 (so that others know that they can use Ch 16 without breaking into someone else's conversation).

geek_mm12345, May 18, 5:05 pm

MM12345. Yes I'm sure it is Wgtn Radio telling someone who has called up on 16 - to go to 71. I then hear Wgtn Radio acknowledge the transmission (on 71) and whatever was said by the other party ( unheard by me)

geek_south9, May 18, 5:26 pm

It would help if you were on the right frequency for a start. 156.575Mhz as I said above.

geek_johotech, May 18, 7:16 pm

Duplex?

geek_moltenfire, May 18, 7:20 pm

Channels? Switching ?

You mean they do not use ZC1's any more ?

geek_tintop, May 18, 7:27 pm

No such locally made quality available these days.

geek_johotech, May 18, 7:32 pm



Perhaps just as well.

geek_tintop, May 18, 8:43 pm

ZC1's use hollow state technology. Bit hard to get hold of for spares nowadays.

geek_ians2, May 18, 9:11 pm

Your pot-cores need tuned.

geek_moltenfire, May 18, 10:19 pm

FYI none of those frequencies or transmissions have anything to do with ham - amateur - radio. In the VHF range hams have the frequencies from 144.000 Mhz to 148.000 MHz (known as 2 metres), and around 430 Mhz - I forget the band limits there as I never used 70cm myself.
There are numerous repeaters on these bands all over NZ, and you can find a list of them on Google if you want.

geek_cjdnzl, May 18, 11:21 pm



As I said above somewhere, Ch 71 isn't Wellington (Harbour or Fisherman's) Radio - it's Maritime Radio. They monitor Ch16 - then instruct the caller to go to 71 (working channel) as Ch16 is a calling channel - to be kept as clear as possible - not clogged up with boats wanting trip reports logged etc. Important - as it's the emergency channel - which all commercial vessels must monitor, and all others should monitor.
If you want to call Maritime radio, you can call them up on Ch16 by default (ie if you don't know which is the best working channel for where you are - as they monitor those too), and they'll tell you which channel to go to. You're hearing Maritime NZ on 16 and 71 because they have a network of powerful stations set up on hills covering (much of) NZ coastal waters, The VHF on board boats are lower power (usually 25 watt max) and have small aerials - so you're just not hearing them - because they're out of range for you.
I expect that whatever antenna you're using with a scanner will not be tuned specifically for marine VHF frequencies - so you're only going to pick up strong signals. It wouldn't surprise me if a $100 hand-held marine VHF with an antenna only a few inches long would be better - as at least that will be tuned.
The private station operators (such as Wgtn Harbour radio) also have land-based stations, usually on duplex channels and set up on hills to give extended range.

geek_mm12345, May 18, 11:45 pm

Hi MM12345.
Tks for all yr guidance - very helpful.
Have now reprogrammed 156.575.
Purchased aerial from Boat Shop - then took to Marine Electronics place to have extension cable attached so could place it outside with lead to scanner inside.
Tks also for ref to VHF frequencies. Found some I could add and some I can remove. Cheers. ))

geek_south9, May 19, 11:58 am

For any further info on marine bands, all info can be found in the PIB 23 Document available from Radio Spectrum Managements website

http://www.rsm.govt.nz/online-services-resources/publications/pibs/23 Referred to as MM71 in the pdf.
if you want to listen to someone in particular, and they have a licence, then search it under licensee

http://www.rsm.govt.nz/smart-web/smart/page/-smart/domain/licence/SelectLicencePage.wdk?fromHome=Yes

Providing they are not on a DMR or P25 digital channel, unless you have DSD decoder etc, then you could listen to them

geek_shall, May 19, 3:38 pm

Tks - SHALL - all too technical for me. )))

geek_south9, Nov 8, 4:13 pm

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