Frequency Question

[Digger22]

[size=medium]Does the Deus coil transmit to its receiver (remote) at the same frequency that it transmits its search signal?, or does it transmit on a separate freq, if so what frequency does it transmit on?[/size]

My guess is that it does transmit on the same frequency, but since I no longer own a RF meter, hence the question.

The above info is needed to calculate the correct antenna length, for shallow water hunting. The book lists an antenna, but I cannot find it anywhere in the us available for sale,

 

[Terry(Mi)]

I have a 6' and a 10' cable. Both work equally as well as the other, so I don't believe length is nearly as important as center wire that's carrying the signal.

 

[Andy Sabisch]

Let's not make this more complicated than it needs to be . . . we went through this a few months back and details on how to make an antenna were provided.

Here is the link to the post that discussed the mod . . .

http://www.findmall.com/read.php?83,1860918,1860918#msg-1860918

The antenna simply carries the signal from the coil to the headphones or control unit - I have used lengths from 5' to 10'+ with no difference in performance.

From that point if yuo are using the control unit, you have it in a pouch / case and there will be a wired phone jack that you plug into.

The key with any mod for water use is [size=x-large]DO NOT GO CHEAP ON THE CASE![/size] Avoid the $8 E-Bay Chinese models that will ensure you are buying a new control unit the first time you use it . . . . spend the money for one proven to remain dry - $50 or less - and you will not be surprised

Andy

 

[Digger22]

All the above is true, and the information I am looking at will not be used in a complicated manner.
The full physical length of an antenna is determined by using the formula 1/Frequency times the speed of light=antenna length.
Now.....the usable length of an antenna would be to divide the antenna length, by either 3/4 (not that efficient),1/2, 1/4, /1/8, 1/16 etc. The truer the length of the coax the more accurate target ID should be.

Some folks are happy with that works for you, it should work for me. I am not one of those people, nor do I want to be. I want things operating at their best so that I can work on my skills. My skills don't have to be perfect, but I want them to be the best that I can make them.

All that being said please refer back to my OP, since the information is not easily available, it could be obtained with an RF meter which I don't have. But I believe their are some practicing ETs who could supply that information.

Andy, I don't think that link gives the information I am looking for, but I'll check it out again.

 

[Andy Sabisch]

I understand that you have an electrical background and that there is a basis for your question but I checked the Target ID's on several targets with the coil submerged so that the signal coming to the control unit was through the antenna and not the air . . . . used a 6' cable, 10' cable and the rest of the 100' roll of RG6 cable and there was no difference in the TID produced by a gold ring, pull tab and quarter.

Be curious as to what you find when yuo get the electrical frequency data you are looking for in terms of designing a new antenna for the Deus

Andy

 

[samandnoah]

Hey Digger 22--

I think I'm a bit like you in terms of precision on issues like this. For me, it manifests itself in my audio hobby obsession. Anyhow, in this case, I'm not sure I see it the same way. This "antenna" isn't as much about trying to pick up a specific freq and transmitting (I've also done ham radio in the past) as much as it is a physical carrier. I think the analogy that comes to my mind is that this "antenna" is acting more like a speaker wire than an antenna. Hence the need to make physical contact both on the coil end and on the control box. So you do care about the thickness/diameter of the conductor carrying the signal relative to the length that you need to carry the signal. But I'm less convinced that the ideal length of the wire is as critical in achieving maximum signal transmission this case.

I honestly am not trying to sound argumentative or like a know-it-all. It's just that I've been thinking about this a lot since I am taking my Deus to the beach and into the water for the first time THIS WEEKEND! So I don't have any first-hand experience on this issue yet, but will soon. Antenna is ready to go. Actually, I will have 2 lengths available, one 4' and one 7'. Since I'm sincerely interested in this issue, I'd love to understand how you would objectively measure the impact of the length of the antenna relative to the theoretical optimal length? Or would it be based on subjective performance measures (like depth of coin in the sand underwater)? I haven't thought about that particular aspect very much, and not sure how you'd do it.

Rich

 

[Ism]

2.4GHz would likely be the frequency. Its not the detection frequency that is used for transmission.
This is not an antenna as you may think, it only reradiates the signal enough for the control box to receive it.
The antenna has to be within an inch or two of the control box and attached to the coil for it to function properly.
Its something that works without spending a weeks salary on a 2.4 GHz repeater.