Yet another Surf PI in the fleet :)

[otov]

hi
its my 4th time that i'm posting... the last 3 was from my mobile phone... its not working!!!
anyhow
brente...
i've liked what you have made with your Md
is it the surf PI from silverdog or other ?
can you direct me
I would love guidance in this matter
regards
omer

[N1PS]

Noise is a frustrating problem when working on some of these projects. If you read some of the TGSL threads, Simon Baker actually went on a Quest to find a location to verify a theory on detector performance and noise. With the TGSL project noise can manifest itself by lack of detecton range. It was not until he took a drive deep into the countryside until he was able to prove it to himself..

I finished a pair of IDXs a short time ago and had trouble with all of my coils (so I thought).. I could not run the sensitivity higher than 25 percent or so.. Just wobbling the coil slightly would cause false signals even in my back yard. THEN.. I took the IDX to a large field far away from my house and to my amazement I could run it wide open and it was absolutely quiet and stable!! I don't worry too much about noise problems when building anymore as I'm tired of banging my head on the workbench trying to figure it out
Good luck with the Surf Pi Peter. It's a nice project.

Don..

Don,

I read that thread....a long one and some of the posts went on tangents. But I found several similarities with the noise noted here. I too had to decouple audio from the power supply, an easy fix. The sensitivity is badly affected by the noise as was reported by one of the posts on that thread, similar to an overload front end of a receiver, I even hear a beat note with a signal and the noise. The noise is random. It varies from day to day. I would like to spend some more time understanding the source(s). I look forward to doing some work and testing.....and getting outside when the snow isn't up to my waist.

Also noted your nice coils and vacuuuuuum forming I think. Are you using ABS? At work we make radomes and frequently use ABS. Excellent RF properties. Though I plan to use fiberglass for the final coil shapes....we work with that too.

TNX

Peter

[dfbowers]

Peter,
Decoupling the audio seems to be a common practice among many designs and as long as there is a regulator somewhere in there the audio is not an issue.. but I have seen where getting a speaker anywhere near the coil causes a loop in the system too. Sometimes replacing the speaker with an LED can tell you things.

I have been ordering ABS from US Plastics for some time in 96" X 48" sheets.. fairly cheap.

Don.

[N1PS]

Finally had a chance to look at the MD again. I'm curious why I cannot silence the chopper tone. This with the threshold set at minimum. A slight increase of this control just creates a steady tone, even when using a resistor as a load. Plan to get at it tomorrow again.