antenna length?
- Thread starter unidcom
- Start date
- Status
Al42
Member
18". http://www.1728.com/freqwave.htm The antenna should be 1/4 the length for the frequency.
jhooten
Member
Those appear to be the whips and springs from a 5/8 wave antenna there should be more pieces.
Do a web search for Larsen antenna web site. They have cutting charts in the tech section.
Do a web search for Larsen antenna web site. They have cutting charts in the tech section.
kf4lne
Member
A cutting chart is great, but the best way to do it is to cut it close, but long and trim to a match using a SWR meter. For receiving only, you can just cut it to a length based on 234/MHz*12=inches to get a 1/4 wl measurement. (234/162.4=1.44ft*12=17.29in)
Yokoshibu
Member
- Joined
- Feb 8, 2005
- Messages
- 362
speed of light (299 792 458 m / s) / (164000000 freq) = (1.82800 meters) * (V factor of coax ??? example fig .89 % ) = (1.626922 meters) * (5/8 wave) = (1.01682 meters)
Those do not look like loading coils, I have seen them before with tinned copper straps on the inside or something similar.
Those do not look like loading coils, I have seen them before with tinned copper straps on the inside or something similar.
jhooten
Member
Whips and springs from a 5/8, the loading coils are missing.
Hi Uni and all,
The picture says nothing but some still are guessing they're some sort of 5/8 wave. My experience tells me they could be HF, VHF Lo or VHF Hi depending on what sort of "base load" coil they have. That can only be determined by reading the label, the frequency range is marked if the label hasn't fallen off. Once that has been determined you must use the frequency cutting chart supplied by the manufacturer, without the above information we're all clueless as you are. Then too like Yoko says they may not be coils at all which would make them 1/4 wave antennas. The long and short of it is we have no idea what we're looking at, I won't even venture a guess and come up looking stupid.
FYI, the chart always puts you spot on the money, no SWR measurement is need because the resonance curve usually puts the 2:1 points at over 4MHz from center.
Jhooten, whips and springs? OOOooo, KINKY!
The picture says nothing but some still are guessing they're some sort of 5/8 wave. My experience tells me they could be HF, VHF Lo or VHF Hi depending on what sort of "base load" coil they have. That can only be determined by reading the label, the frequency range is marked if the label hasn't fallen off. Once that has been determined you must use the frequency cutting chart supplied by the manufacturer, without the above information we're all clueless as you are. Then too like Yoko says they may not be coils at all which would make them 1/4 wave antennas. The long and short of it is we have no idea what we're looking at, I won't even venture a guess and come up looking stupid.
FYI, the chart always puts you spot on the money, no SWR measurement is need because the resonance curve usually puts the 2:1 points at over 4MHz from center.
Jhooten, whips and springs? OOOooo, KINKY!
jhooten
Member
The radio hobby has uses in all aspects of our daily life.
(humm it looks like my sig line has disappeared again)
(humm it looks like my sig line has disappeared again)
- Status
Similar threads
