Carl, Question about recommended RX gain

[magic]

I understand that the recommended Rx gain feature will be gone on the upgrade to the V3i. My question is that for a long time I was searching and asking about how to test a coil to see if its bad. I never had anyone tell me anything other than send it in. Then, with the V3 came this... http://www.findmall.com/read.php?66,1161702
I was pleased to know how to test my coils now. I had two coils that I just sent in and you replaced them for me. They did not overload when maxed out but the best RX gain I could get in the air was 5 or 6 at best.
With this being said, If I get the upgrade and the recommended rx gain feature is gone, How can I test my coils? That feature is really only used by me to test my coils and I like being able to do that. Is there another way I could test if I get the upgrade? If I only went by if the coils overloaded, I would still be using bad coils. By the way, The ones you sent me back are excellent! They made my V3 come alive again!

 

[Larry (IL)]

The coil test does not use the recommended RX gain Magic. Anne even states the Probe (sensitivity zoom) is not the way to test coils.




1 The best way to check your coil is to set your RX gain to 15.

2 Turn TX Boost on with the coil in the air (not on the ground or around other metal).


3 If you don't get an overload, your coil is good.

 

[magic]

Larry, I understand this. Rob told me I should ask this question and see if Whites will respond.
As it states in the coil test section that you posted.....

White's will consider any loop that has a recommended gain of 8 or more in air to be a good loop. Carl

Like I said, mine did not overload and the only thing I had to go on was that mine would not let me get a recommended gain of more than 5 or 6 in the air.
I know that if someone is having trouble with there machine, the first thing they are ask to do is check the coil. Soooo.... is now the only way to check a coil is just see if it overloads at max? If thats the case, then my old coils would have tested good. But Whites said they were bad.

 

[Rob (IL)]

Rob told me I should ask this question and see if Whites will respond.

We deleted Magic's post with the trouble makers post. I didn't want his post to be deleted and didn't have the answer to his question. All my bad coils would overload. I've not seen Magic's problem so don't know if it is common or not. [attachment 160223 Reading.gif] Rob

 

[Schultzie]

I had a coil (D2) that would only recommend an Rx of 4 but wouldn't overload when maxed out. I wasn't getting very good depth though and a White's Engineer said it was a bad coil and to send it in for replacement. I received the new coil and checked it out. I did the test and it recommended an Rx of 15 and didn't overload when maxed out with Tx Boost on. I do not know what the difference was within the coils but I am getting good depth now. Just my situation if it helps any. Good luck!

 

[Jungle Jim]

n/t

 

[yazoo]

n/t

 

[magic]

n/t

 

[andreak77]

This is the advice I give my customers:
Using the recommended rx gain is not a reliable way to check whether your coil is good or bad. Ignore the suggested RX gain and run your RX gain as high as possible while maintaining stability.
And a low "recommended" RX Gain is not a sign of a bad coil - if you can run it with a higher setting then your coil is fine, if it doesn't overload when doing the coil test your coil is fine.


Example - One customer always had a recommended rx gain of 1 or 2 but he could run it always run it at 13, 14 or 15 with no problems - so his coil was good. Another would receive a recommendation of 12 but he couldn't run it past 4 without the unit overloading - he had a bad coil - the coil test proved this as well.

This was the reason for the air test of RX Gain at 15 and TX Boost on - if it can handle those settings your good to go because the unit cannot be set any hotter.

 

[Rob (IL)]

Guys they are busy now. I'm sure they aren't reading the forums right now. What Andrea is telling is true. Rob

 

[magic]

andreak77,
I understand all of what you said but,
I know from what I have been reading that people are having problems with the D2 coil and the epoxy issues.
I personally have had 3 different D2 coils. They seemed to start out great and then over time they went bad. I am not an expert and don't know why they went bad.
Carl was quoted as saying.. White's will consider any loop that has a recommended gain of 8 or more in air to be a good loop.
I take this as opposed to any coil giving a suggested RX gain of 7 or below in the air to be bad.
I don't really know that is why I am asking. I know my coil I just sent in would not give me a suggested RX gain in the air over 5 or 6. It would NOT overload at rx 15 and tx boost on.
It just didn't act right and the RX gain test is the only thing I had to go on. My main question is still not really answered....which is... What can we do to test to see if a coil is bad or going bad rather than send it in for testing? It seems to me that the rx gain test was useful in my case for testing. I may not get the upgrade just because of this one feature being taken away because it seems to be a useful tool in determining if my coil is bad or going bad.

I know you say its not a good test yet it was posted as a way to test and I am sure its the only way people know how to test at the moment.
Is there another way?

 

[andreak77]

You said "I know my coil I just sent in would not give me a suggested RX gain in the air over 5 or 6. It would NOT overload at rx 15 and tx boost on", however you did not state whether or not you could run your detector reliably at higher rx gain settings?

I don't know how you can use the "suggested RX gain" as a test because it is not a true measurement of the settings the coil can handle?

Carl stated this "...this is based on a target residual of 10% and there is no real need to run this low. You can easily run a loop that has a recommended gain of 8 all the way to 15 with no problem. Replacing such a loop with a more perfect loop would not offer any performance difference." - I think these two statements identify what is missing in this whole equation.

So even if your coil gives you a recommended gain of 5 or 6 - if it's good (coil test: rx 15, TX boost, no overload) you should be able to run it with higher settings - settings as high as possible while remaining stable without overloading. On a V3i - do the coil test and then run your rx gain as high as possible while maintaining stability - that is your test.