Hey Dave J. search coil temperature question

[Mike Hillis]

How long do I need to wait for my search coil temperature to achieve ambient temperature?

This is in regards to dealing with false responses caused by temperature differences.

Can you give us a little wisdom on the topic?

Thanks in advance.

HH
Mike

 

[Dave J.]

Could you be more specific on what "false responses" you're referring to? From the electrical design perspective the only temperature variable we're normally concerned with is the resistance temperature coefficient of the copper in the transmitter circuit, which we either minimize and/or temperature compensate depending on the product, such that the resulting effect on ground balance is rarely of sufficient magnitude that a user would notice if not specifically looking for it.

 

[DirtyJohn]

I remember when I got my F75 in after having the upgrade done. It came back during winter here in Illinois. The package arrived and the detector was cold.

After I assembled it and hooked the coil up and turned it on, it went bonkers. I couldn't ground balance or calm it down at all. Unfortunately I was so angry about this I posted about it on another forum.

About 3 or 4 hours later I was getting ready to package it back up to send back to Fisher. I decided just out of curiosity to turn it back on because it was cold when I got it. I turned it back on and it was nice and stable, ground balanced like it was supposed to and was basically good to go. I did go back on my forum post and apologized and explained that it was fine.

It seems temperature does indeed make a difference in how the detector acts.

HH
John

 

[togg77]

So DirtyJohn have you used your 75 in cold weather since and if so how did it perform? Thanks.

 

[rockyj]

The copper in a super cold coil can change balance as the copper shrinks..as it warms up it goes back into balance. as the copper expands.