New amp questions

[rutledj]

I built a blues jr clone and am wondering if it is normal to have a lot of hiss in the amp? It is a very bright sounding amp anyway (is that normal) but if either the vol or master vol is maxed out you have a lot of hiss.

Also, I have a problem when the guitar is plugged in and guitar vol on 0, you can pick up a radio station. I've read about putting a cap from input sleeve to chassis but I'm using a metal jack that is already mounted to the chassis. Should I switch to an insulated input jack?

Thanks,
Rut

[v00d00blues79]

Are you running any shielded cable from the input to the grid of your first stage? This would/should help cut down on the RF.


Just my .02c

Andy

[Structo]

Do you have shielded cable from the input jack to V1?
And from the volume pot to tube?

What size grid stopper do you have on V1a?

[rutledj]

Yes. I'm using shielded wire. The grid stopper is as per schematic (10k).

[Structo]

Try raising the grid resistor to 33K.

Do you have your cable shield grounded only at the jack?

I hate using a RF cap on a input but if you have a nearby radio station it may be your only course.