Stable Threshold??

[ArDirtSlinger]

I bought a used GPX 4500 back in Dec. At times while hunting in an urban envirioment it is very difficult if not impossible to get a stable threshold. Most of the time it pulsates and when I am able to get it lined out it will all the sudden go haywire. I have recovered relics like this but it is mentally draining to listen to all that crap.
Is this indicative of these machines or is the circuitry going bad? Setup wrong? Im using settings from Minelab video on setting up the 5000 for relic hunting. Or coil damaged? I am using the 12 DD minelab coil that came with it. It also came with a Gold Screamer which I'm using.
I consider myself a newbie with this machine so any advice is appreciated.

 

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[ChampFerguson/TN]

I bought a used GPX 4500 back in Dec. At times while hunting in an urban envirioment it is very difficult if not impossible to get a stable threshold. Most of the time it pulsates and when I am able to get it lined out it will all the sudden go haywire. I have recovered relics like this but it is mentally draining to listen to all that crap.
Is this indicative of these machines or is the circuitry going bad? Setup wrong? Im using settings from Minelab video on setting up the 5000 for relic hunting. Or coil damaged? I am using the 12 DD minelab coil that came with it. It also came with a Gold Screamer which I'm using.
I consider myself a newbie with this machine so any advice is appreciated.

I've never swung a 4500, but you have to set up every machine every time at different sites. Try experimenting with your settings as One Size definitely doesn't fit all ground. On clean ground, start with lowering your sensitivity to near zero, then gradually increasing it until your threshold starts to break up. Then back it off a hair until it is stable.
As I said, I don't know the 4500, but after setting your sensitivity/threshold you can start tweeking your other setttings to find what works in that ground on that day.

 

[Terry Soloman]

Reduce your RX Gain until you get a stable Threshold.

https://www.minelab.com/__files/f/3965/4901-0063-1.1 Instruction Manual GPX-4500_screen.pdf