Low band radio antenna help - Steel Soldiers::Military Vehicles Supersite

emmado22 · 12-02-2009, 22:38

All,

It's not exactly military radio related, but can a low band mobile radio that TX and RX's in the 46 MHz range at 60 watts be mated to an old school "CB ball type antenna mount with 102 inch antenna" that has been cut down to the right length for the 46 MHz freq??

I need to mount a modern low band radio (hidden from view) on an old 1950's jeep, and the antenna mount needs to look the part being from the 1950's.... I figure the "CB antenna ball" looks kinda period looking..

Any ideas?

800summit · 12-02-2009, 22:53

Are you sure the antenna is cut for 46mhz and not 46 khz?
if so you are good to go. Otherwise you can go to Tessco.com and order part# 460448 Model # NM050C which is rated for the 47-54MHZ at 200watts. comes with the load coil and 50" stainless whip. This is a unity gain 1/4 wave . Hope this helps

emmado22 · 12-02-2009, 23:13

yes, it's 46 MHz Low Band.

I saw those antennas also, but the look modern.. Im thinking the 102 inch antenna on the ball mount cut down to size for the 46 MHz would look 1950/1960's ish..

m38inmaine · 12-03-2009, 01:42

CB is in the 27MHz range, so you would have to cut it about in half, you would need a swr meter and start cutting "long" untill you get it cut to the correct length. But yes it will work.

tennmogger · 12-03-2009, 18:20

I use one just like that on 52.525 Mhz, a cut down CB whip.

Bob WB4ETT

Quote:

Originally Posted by emmado22

All,

It's not exactly military radio related, but can a low band mobile radio that TX and RX's in the 46 MHz range at 60 watts be mated to an old school "CB ball type antenna mount with 102 inch antenna" that has been cut down to the right length for the 46 MHz freq??

I need to mount a modern low band radio (hidden from view) on an old 1950's jeep, and the antenna mount needs to look the part being from the 1950's.... I figure the "CB antenna ball" looks kinda period looking..

Any ideas?

Carl_in_NH · 12-03-2009, 18:35

Do yourself a favor and bond body panels together in the area of the antenna mount using a good, wide braid with lugs soldered on (not crimped) - and bond the body to the frame in a couple places, too. That gives your antenna a counterpoise to work against.

46 MHz isn't hard to deal with - given the physical sizes involved in a quarter wavelength. As you go lower in frequency, the antennas become more of a compromise - and the details of bonding and grounding become more important.

319 · 12-03-2009, 20:22

Not a radio guy, but does the wattage (60 in his case vs 5 or 10 for a CB if I recall) make a difference in regards to what type of antenna?

Carl_in_NH · 12-03-2009, 20:29

Quote:

Originally Posted by 319

does the wattage (60 in his case vs 5 or 10 for a CB if I recall) make a difference in regards to what type of antenna?

Not really; the higher power will result in more voltage across the mounting insulator - but it shouldn't be an issue for any decent ball-mount.

A 1/4 wavelength whip antenna is what this application calls for. At 46 MHz, it's short enough to not even need a spring at the base (unless you really want one).

There is one caution, however; don't grab onto the antenna when transmitting 60 watts in the VHF region. You _will_ get an RF burn - and they are painful.

emmado22 · 12-03-2009, 20:33

Thanks for all the help. Yep, RF burns are no fun. I learned that one in the Army one day, grabbing on a vehicle antenna by accident when the driver was TXing.

rlwm211 · 12-04-2009, 00:45

The appropriate length for a quarter wave is 61" for 46 MHz. The next trick is to make sure your coax length is correct for the frequency so the SWR is the lowest possible for your rig. Let me know what type of coax you are using and I can figure out what length it needs to be.

Hope this helps

RL