Robin2
Well-Known Member
Is it possible to connect a handheld VHF to a masthead antenna (while one is on the boat !) and if so is it necessary to buy a particular type?
Mast antenna for handheld VHF
- Thread starter Robin2
- Start date
vyv_cox
Well-Known Member
Yes it is. I have an adaptor that takes a bayonet antenna fitting on my old hand held and converts it to the fitting used for fixed VHF sets. Unfortunately the old hand held is dead and the replacement has a screwed antenna fitting. That's life.
Twister_Ken
Well-Known Member
Supplementary question
Giving that the h/h is pushing out a max of 5 watts, now down a long cable (so maybe some losses?) how much difference does it make to the range to route it through a m/head aerial?
Giving that the h/h is pushing out a max of 5 watts, now down a long cable (so maybe some losses?) how much difference does it make to the range to route it through a m/head aerial?
dickh
Well-Known Member
No problem, I have used a masthead aerial on a H/H VHF - easily raised Thames CG at 15 miles when I had a small emergency... You can get an adapter for the bayonet fitting on the H/H to the large screw fitting on the aerial - try people like Tandy or RS, cheaper than a chandlery.
dickh
Well-Known Member
Additionally make sure the aerial cable is best quality or you will get losses as previous posted.
steve_cronin
N/A
You need
A BNC connector, a female PL259 line connector and a length of RG 58 co-axial RF cable.
Make this up into a patch lead. The BNC will fit in place of the "rubber duck" hand-held's antenna. Connect the other end to the PL259 -plug on the end of your masthead antenna lead and away you go!
The small loss up the extra length of cable up to the masthead willbe far outweighed by the better siting of the radiating antenna. Remember that your main set transmits on 1watt reduced and this can get you surprising distances.
i always carry this patch lead as a safety item just in case the main set or ship's domestic batteries pack up.
Steve Cronin
A BNC connector, a female PL259 line connector and a length of RG 58 co-axial RF cable.
Make this up into a patch lead. The BNC will fit in place of the "rubber duck" hand-held's antenna. Connect the other end to the PL259 -plug on the end of your masthead antenna lead and away you go!
The small loss up the extra length of cable up to the masthead willbe far outweighed by the better siting of the radiating antenna. Remember that your main set transmits on 1watt reduced and this can get you surprising distances.
i always carry this patch lead as a safety item just in case the main set or ship's domestic batteries pack up.
Steve Cronin
Bergman
Well-Known Member
Re: Supplementary question
Range will be significantly better on mast heaqd aerial than on H/H rubber duck.
Provided good quality co-ax of correct impedance and good quality connectors are used.
Loss in properly matched feeder is quite small at 156MHz.
Dropping from 25 watts to 5 watts is just over 6dB. In Ham speak thats 1 "S" point on scale 1 - 9
On 30 MHz Ham band I have worked easily into USA from UK on a converted CB set and car aerial. Don't need lots of power.
Range will be significantly better on mast heaqd aerial than on H/H rubber duck.
Provided good quality co-ax of correct impedance and good quality connectors are used.
Loss in properly matched feeder is quite small at 156MHz.
Dropping from 25 watts to 5 watts is just over 6dB. In Ham speak thats 1 "S" point on scale 1 - 9
On 30 MHz Ham band I have worked easily into USA from UK on a converted CB set and car aerial. Don't need lots of power.
Robin2
Well-Known Member
Re: You need
Thanks to everyone for all the help. I am no stranger to the Maplin catalogue. I just wasn't sure if it was a simple as it clearly is.
Thanks to everyone for all the help. I am no stranger to the Maplin catalogue. I just wasn't sure if it was a simple as it clearly is.
trevor
Active Member
Re: Supplementary question
RG 58u Coax has a loss of about 3db per 10 metre length this means that your output power will be reduced to 50%, however the increased effiency of the mast head antenna should compensate for this.
Dont worry too much about the reduced power output since power/range work on an inverse square rule i.e. to double the range you must increase the power by 4 times.
More important is the received signal strength since here the reduction of received signal is proportional to the loss in the cable. But again the mast head antenna should take care of this
Hope this is useful and not too electronically technical!
Trevor
RG 58u Coax has a loss of about 3db per 10 metre length this means that your output power will be reduced to 50%, however the increased effiency of the mast head antenna should compensate for this.
Dont worry too much about the reduced power output since power/range work on an inverse square rule i.e. to double the range you must increase the power by 4 times.
More important is the received signal strength since here the reduction of received signal is proportional to the loss in the cable. But again the mast head antenna should take care of this
Hope this is useful and not too electronically technical!
Trevor
ccscott49
Well-Known Member
You can buy adaptors from maplins, you may need to adapt a couple of times, to get to the right fitting, but it can be done! Dont worry about losses, hieght of antenna is the main thing, not power.
