How to figure what bands my antenna is built for

[KF0AWL]

I bought a W2AU Big Signal 1:1 Balun with legs already on it at a hamfest. I cant remember what bands the guy said it was tho.
How do I figure it out again? 🤔

 

[AJAT]

I bought a W2AU Big Signal 1:1 Balun with legs already on it at a hamfest. I cant remember what bands the guy said it was tho.
How do I figure it out again? 🤔

Is this the one? W2AU Series Baluns & Isolators

 

[KF0AWL]

Ya thats the balun but the legs look factory tuned. And it don't say anything on the balun what freq its made for

 

[n5rv]

468/total length in feet end to end= Freq in MHz

 

[KF0AWL]

468/total length in feet end to end= Freq in MHz

Now that you say that I realized I had read that somewhere 🤔 but thank you pointing it out...

 

[belvdr]

468/total length in feet end to end= Freq in MHz

It should be noted that is for a half wave dipole. I always read 492 as the constant, but it's probably not critical. It will get you in the ballpark.

 

[jhooten]

It should be noted that is for a half wave dipole. I always read 492 as the constant, but it's probably not critical. It will get you in the ballpark.

In free space yes. 468 accounts for the differences in the velocity of propagation of the wave in free space and a metal conductor, and other variables.

 

[dlwtrunked]

In free space yes. 468 accounts for the differences in the velocity of propagation of the wave in free space and a metal conductor, and other variables.

The equation is 0.5*c*vf/f, where c is the velocity of light in a vacuum (*exactly* 299792458 m/s or approx 49178511 ft/s), vel_fact is the velocity factor (*which will not be know exactly and that is going to drive the accuracy of the final calculation probably to about two digits*), f is the frequency in Hz, and the 0.5 is for half-wavelength (use 0.25 for quarter wavelength). For bare copper wire, the velocity factor is about 0.95, resulting in 467/f. If one uses the above, ones comes up closer to 467 than 468. The 468, besides maybe being easier to remember, goes back to the historical use of a slightly high rounded off value for the speed of light in the metric system (using 3x10^8 m/s instead of the now defined exact value of 2.99792458x10^8) and converting the result there from metric to English units. But since the result is only going to be accurate to about 2 digits, it is not going to make a real difference.

 

[mass-man]