Antenna on desk

[Heyboy]

I have a Kenwood TM-271 on my desk with a MFJ-1740 antenna mounted on a piece of PVC also on my desk about two feet above my head. My question is how far should the antenna be from my head?

I wasn't concerned until I keyed up on a new frequency and my paper shredder started!

This is all new to me so be gentle.

Thanks in advance for your assistance.

 

[n9mxq]

And how is everything grounded? If you keep the power on low, I wouldn't be too concerned. But more separation would be advised for higher power.

 

[HamBanjo]

HIA.......
I do know, and you'll hear it again...... as far away from you as you can, and or limit your talk time...

start looking up tx exposure and antenna basics....

good luck and 73

 

[WB4CS]

Wow. Okay. Since you're new, I'll not give you too much grief lol.

First, depending on how the antenna is mounted to the PVC, you may not have an electrical ground or ground plane. This can cause some SWR issues of the antenna when transmitting. Additionally, as you should know, high SWR can cause damage to your radio. Does your radio get really hot when you transmit? If it does, your SWR may be very high.

Second, as others have mentioned, the antenna should be as far and high from you as possible. On 2 meters at 50 watts, you should be at least 4 feet from the antenna. This distance can be shorter in a car because the metal frame of the car provides some protection from RF exposure.

Here's one good reference for RF exposure limits: RF Exposure Limits for Amateur Radio operators

The FCC has some good info here: http://transition.fcc.gov/oet/rfsafety/

If I remember (but could be wrong) I believe FCC rules part 97 (which every ham operator must be familiar with) covers RF exposure.

Your best bet is to get the antenna outside. If it has to stay indoors, run at low power and limit transmit time to a minimal amount. (Or wear a tin-foil hat to protect your brain from RF exposure )

 

[Jimru]

If you can't put the antenna outside, do you have access to an attic?

Is there another (unoccupied!) room at least? You could set up your antenna in there on as-needed basis on a tripod.

How about a window air conditioner unit? If so, using a magnetic-based antenna (known as a "mag-mount") outside and on top of the A/C unit can be effective for 2 meters (vhf) and 70cm (440 MHz range). One advantage to the A/C setup with a mag-mount antenna is that the metal of the A/C acts as a ground plane, or counter poise, to help minimize SWR (Standing Wave Ratio: http://en.m.wikipedia.org/wiki/Standing_wave_ratio ).

As has been said here previously, if your present antenna is mounted only to PVC, but is not properly grounded or if there is no ground plane, it's bad for the radio, and not so great to have two feet away from your noggin!

Welcome to Ham Radio!

73,
Jim KC2LMH

 

[robertmac]

I thought a lot of this was discussed in becoming an amateur radio operator. If not, generally covered in the Factory Manual. Simply put, most radio manuals state, if parked, do not transmit when some one is walking close to the vehicle. There are a lot of web sites that Google will display on RF exposure. And I would hazard a guess that it has already be discussed somewhere on RR or most amateur radio sites. People are often concerned about the 0.3-0.6 watts that a cell phone outputs when it is near ones head. I would assume the 271 has a heck of a lot more wattage output than a cell phone.

 

[Violation]

I have a Kenwood TM-271 on my desk with a MFJ-1740 antenna mounted on a piece of PVC also on my desk about two feet above my head. My question is how far should the antenna be from my head?

I wasn't concerned until I keyed up on a new frequency and my paper shredder started!

This is all new to me so be gentle.

Thanks in advance for your assistance.

I have the same problem. Everytime I go to my garage radio room, the refrigerator opens.....

 

[prcguy]

I have a caliberated RF exposure meter and for 5w VHF and 4w UHF handheld radios with typical rubber duckie antennas 2" or less exceeds the OSHA 5mw/cm2 level over a 6 minute period. A distance of 4" or more will usually fall under the OSHA level.
prcguy

 

[N4KVE]

How about the antenna being so close to the radio, or power supply. Can this affect anything?

 

[WB4CS]

I thought a lot of this was discussed in becoming an amateur radio operator.

Depends on the study material used to get licensed, or if a person just memorizes the Q's & A's. Part 97 rules covers a little bit about RF exposure, and tells us that as hams we are responsible for knowing about safe exposure limits in regards to our station.

 

[Heyboy]

Thanks

Thank everyone for your input...the antenna is now in the attic and everything seems fine now.

Thanks all.

 

[WB4CS]

Thank everyone for your input...the antenna is now in the attic and everything seems fine now.

Thanks all.

Good deal! You should notice an increase in performance now that the antenna is up a little higher.

 

[Jimru]

Thank everyone for your input...the antenna is now in the attic and everything seems fine now.

Thanks all.

Great!

Heyboy, you still want to be sure that you aren't getting excessive SWR, which can damage your transceiver.

If you haven't already done so, purchase a SWR/power meter (be sure that it's for the frequencies you are operating on, and can handle the output power levels you plan to operate at) and hook that up between your antenna and your radio.

73,
Jim

 

[k9rzz]

Awww. I'm too late. I was going to ask if your eyes went cross-eyed when you keyed up.

 

[KD8TZC]

I understand you are new, and so was I not long ago, so I understand where you are coming from. Some good stuff has been stated above, so I won't go into the exposure and all that.

I too tried to keep my antenna and rig really close together. I had a 10M dipole on the wall inside my office and the rig right below it. I had so much RF in the shack it wasn't funny (and the SWR was sky high). On top of this, I too started to see funny things happen every time I keyed up the mic. I had two PC's in the room (one of them across the room, and the other right next to the rig) and the one would just shut down, and the other would make strange noises every time I used the mic.

Moral of the story is, get the antenna away from the rig if you can. I had to move my shack to another part of the house, but once I did, my SWR came way down, and I no longer had the problems I was seeing.

Best of luck and 73's,

 

[k3cfc]

I have a Kenwood TM-271 on my desk with a MFJ-1740 antenna mounted on a piece of PVC also on my desk about two feet above my head. My question is how far should the antenna be from my head?

I wasn't concerned until I keyed up on a new frequency and my paper shredder started!

This is all new to me so be gentle.

Thanks in advance for your assistance.

If you put a 5 watt florescent NOT CFL tube under your antenna and it lights up when you transmit your being exposed to dangerous rf radiation.