Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: joesatch on January 15, 2022, 11:08:48 pm

Title: 2204 V1 static when i touch the tube
Post by: joesatch on January 15, 2022, 11:08:48 pm

only on V1. Is this normal? I tried swapping tubes. Ground issue or something else? Newish build so i dont think it's a deoxit situation. Using EH 7025 tubes (low noise). Tried others but all the same. Somewhat like touching the end of a guitar cord when the amp is on but not as loud.

Title: Re: 2204 V1 static when i touch the tube
Post by: PRR on January 16, 2022, 12:45:32 am

Don't do that.

Title: Re: 2204 V1 static when i touch the tube
Post by: shooter on January 16, 2022, 03:53:06 am

Forgot most of the cool names but I think it's called "electro-static interference"
surf it up
 I have the nasty ability to walk past radio's n get a good signal fade/interference. 

Title: Re: 2204 V1 static when i touch the tube
Post by: 66Strat on January 16, 2022, 10:03:06 am

Quote from: shooter on January 16, 2022, 03:53:06 am

Forgot most of the cool names but I think it's called "electro-static interference"
surf it up
 I have the nasty ability to walk past radio's n get a good signal fade/interference.

Handled too many CT tubes? :icon_biggrin:

Title: Re: 2204 V1 static when i touch the tube
Post by: HotBluePlates on January 16, 2022, 10:25:59 am

Quote from: joesatch on January 15, 2022, 11:08:48 pm

only on V1. Is this normal? ...

Yes.

YOU are an RF-antenna.  You're bringing an RF source close to the highest-gain high-impedance spot in your amp when you touch V1.  So of course you get a noise happening.

Which is why PRR simply said, "Don't do that."

Title: Re: 2204 V1 static when i touch the tube
Post by: shooter on January 17, 2022, 04:08:23 am

Quote

Handled too many CT tubes?

those just blew out my back  :sad2:


MRI systems are where some wonky sheet happens!
one Cal was on a receiver module that sat in the High Field, the adjustment was in Hz, getting within a foot of the module would shift frequency 10KHZ!  Typically took a 1/2hour to adjust a "bias pot" < 1/4" to find the "sweet spot"  all while bouncin your brain in and out of the field so you could verify you're adjustment was in spec... or not!