Base antennas ?

[Oatmeal]

Bought me a HF radio and now would like to no what all bands can I use the Imax 2k on ?....
Any you guys using this antenna ?...

Also, I have a Maco 3 element beam, should I keep this beam and tune it for the 10m band, or just sell it ?..
What do you guys recommend me doing with the beam ?

 

[n8fgb]

If you do have , or are about to get, general class privileges, then sell it and buy a used tribander. Your rotor should be able to turn a small one. Your I maxx may work on 15 and 17 meter.
Rich

 

[M0GVZ]

The Imax 2000 will do 10-15m without tuning. Your Maco will work fine on 10m. I would keep it.

 

[Oatmeal]

Cool, the beam is new still in the box...
The Imax, has a 1.1 swr on 28.305.00 to 28.500.00....when I talk the swr peaks at a 2....this was with the rf power set on a 100 watts, thats what the factory had it set at.....so guess its ok to use on this part of the 10m band..

 

[wavrider]

the imax will work 10/11/12/15 meters no antenna coupler required

 

[BBB]

You need not concern yourself about SWR readings when modulating (speaking) only when you key (transmit a carrier) and that should be without any mic gain (audio) present when you check it.

I always get a laugh when a local operator says "My SWR's are swinging up too high on the peaks, somethings wrong"

 

[M0GVZ]

You need not concern yourself about SWR readings when modulating (speaking) only when you key (transmit a carrier) and that should be without any mic gain (audio) present when you check it.

I always get a laugh when a local operator says "My SWR's are swinging up too high on the peaks, somethings wrong"

That is completely and utterly wrong. The SWR matters at all times. If the antenna is installed correctly it should not rise as the power goes up, such as on peaks. If the SWR is rising as the power goes up, "swinging up too high on the peaks" as it were, something IS wrong. It suggests there is an insufficient ground plane for the antenna to work against.

On SSB if you transmit with no audio you are putting out no power. The presence of audio when checking SWR makes absolutely no difference.

 

[222DBFL]

What I believe the issue is about the entire VSWR going up, yes it will on a meter that is not self calibrating or that can measure modulated peaks. If you were to told a modulated tone and set the meter to that peaked tone then no the VSWR should not rise. The injected tone will however needs to be held a same level while calibrating. That's just my thought about it all. Good day!

 

[The DB]

That is completely and utterly wrong. The SWR matters at all times. If the antenna is installed correctly it should not rise as the power goes up, such as on peaks. If the SWR is rising as the power goes up, "swinging up too high on the peaks" as it were, something IS wrong. It suggests there is an insufficient ground plane for the antenna to work against.

On SSB if you transmit with no audio you are putting out no power. The presence of audio when checking SWR makes absolutely no difference.

What if the person measuring SWR is using a single needle SWR meter where it has to be calibrated? On that type of meter, with an AM or SSB signal, weather or not SWR actually changes, simply modulating the signal will cause SWR to appear to change.

To actually measure SWR while modulating an AM/SSB signal you need either stable tone (preferably two non-harmonically related tones), as mentioned above, or possibly a dual needle SWR meter that will show both the forward and reflected power at the same time. Neither of which are commonly used on the CB side of radio.

And for the record, a voice saying "ahhhh" is not considered a stable tone for anyone who thinks that it is "good enough".


The DB

 

[M0GVZ]

What if the person measuring SWR is using a single needle SWR meter where it has to be calibrated?

The SWR hasn't changed as you know but all that has changed is the meter incorrectly displaying what it is. That is operator error.

Most of us have smart phones and there are numerous free audio tone generators for all the smartphone platforms that can be used to generate a stable 1kHz tone at a fixed volume.

 

[midnight special]

harmonics from a modulated signal can make you see false readings of the vswr.........................

 

[The DB]

The SWR hasn't changed as you know but all that has changed is the meter incorrectly displaying what it is. That is operator error.

Most of us have smart phones and there are numerous free audio tone generators for all the smartphone platforms that can be used to generate a stable 1kHz tone at a fixed volume.

I think the words "operator error" may be a bit harsh as the limiting factor isn't necessarily the operator, it is how the typical SWR meter used on CB frequencies functions. Although most operators will not know the difference, or how to get an accurate reading in such a case.


The DB

 

[The DB]

harmonics from a modulated signal can make you see false readings of the vswr.........................

If the signal is properly modulated this is not correct. The harmonics will be within a certain range of the indicated or "carrier" frequency.

That being said, if you are running that signal through an amplifier and over driving said amplifier, or running the chips within it out of specifications in any number of ways (you know, like pretty much every CB amp around is run on a pretty much daily basis) then yes it can affect the SWR because there are emissions where their shouldn't be. How much it affects the SWR depends on the antenna. The a99, for example, is going to be much more forgiving of these signals and transmit more of them resulting in a lower SWR than a Maco v5/8 which has a much narrower bandwidth, and thus is more likely to reject said signals, which will also give the appearance of a higher SWR.

In either case, if you have this problem you really should see about getting it resolved, not that many who have this problem are aware of the issue...


The DB

 

[Oatmeal]

The Imax 2k, I bought it new a few years ago I set the swr on it and used it on the 11m band....I set the swr on channel 20, 27.2050, and the swr was all good on the upper end of the band, because at the time I used to talk dx on 28, as well as the ssb channels from 36 up...and the swr was running a 1.1 or less with out running power on it, and with 2 amps I used to run the swr went up a little to a 1.3, never went any higher....

After I bought that 2995dx, I started using it on the 10m band, this is when I noticed the swr on the 10m band, and it was running a 1.5 or less from 28.305.00 through 28.500.00 ....

Over the years I owned his antenna, I have moved it couple times to a different location I taped the rings up so they didn't move any.....and even now with this FT 450d, the swr is the same on the 10m band, nothing has changed....

But have noticed as I have checked the swr on 12m band the swr has changed, guess this is due to the swr not been set for this part of the band...so after it warms up I plan on taking the Imax down and setting the swr on the bands I can use it on....

Just getting started in the HF radio stuff, and I do like to fool with antennas, more than anything else......I'm sure you guess already no this since I used to have a line setup here that some of you didn't think it worked...

 

[wavrider]

http://www.eham.net/reviews/detail/1376?page=1

10 pages of reviews on imax2k.

notice that 12 meters is not that great as far as a vswr or impedance for those who are antenna purists and have nothing better to do that be arm chair agitators and instigators..

the i2k will will present an acceptable vswr less than 2:1 on 12 meters.

It somewhat performs, a dipole will usually out perform it.

the I2K is what it is, and it will allow you to make contacts and several bands without using an antenna coupler.

It is not a monoband yagi nor should it be expected to
perform as such.

It is not a dipole horizontal polarized nor should it be expected to perform as such.

It is a vertical, that is in expensive, light weight, and allows multi band usage without the added expense of an antenna coupler.

If you try to tune the i2k for the 12 meter band you may/will change the impedance of the other bands.