Hi, when adjusting a primary and secondary screw on a IF Trans are you suppose to use a insulated screwdriver? On some of them when you touch the can while adjusting you get no noise and they adjust just fine. On other ones you get static and all kinds of noise is this normal or is there a short somewhere? Thanks Again, George

George: Well, I think the standard advice would be to use an insulated tool, like is sold for TV tuners. But, as you say, it's often unnecessary.

Some IF xfmrs have B+ voltage on the adjustment screw. Those can give you a nasty shock or you can wind up shorting the B+ to the xfmr's metal can. It seems like I've encountered that mostly on older superhets and with IFs that have an adjustment screw on the side of the can? Don't hold me to that, though.
Doug

:Hi, when adjusting a primary and secondary screw on a IF Trans are you suppose to use a insulated screwdriver? On some of them when you touch the can while adjusting you get no noise and they adjust just fine. On other ones you get static and all kinds of noise is this normal or is there a short somewhere? Thanks Again, George

Hi Doug,

I am curious, do you remember the make/model of radio that had B+ on the adjustment screw of the IF trimmer?

Gary

:George: Well, I think the standard advice would be to use an insulated tool, like is sold for TV tuners. But, as you say, it's often unnecessary.
:
:Some IF xfmrs have B+ voltage on the adjustment screw. Those can give you a nasty shock or you can wind up shorting the B+ to the xfmr's metal can. It seems like I've encountered that mostly on older superhets and with IFs that have an adjustment screw on the side of the can? Don't hold me to that, though.
:Doug
:
::Hi, when adjusting a primary and secondary screw on a IF Trans are you suppose to use a insulated screwdriver? On some of them when you touch the can while adjusting you get no noise and they adjust just fine. On other ones you get static and all kinds of noise is this normal or is there a short somewhere? Thanks Again, George

Gary, I don't remember the specific radio model.

The one I'm thinking of (and the one that shocked me) had relatively large rectangular IF xfmr cans.

I suppose it's possible that B+ could be on the adjusting screw, even though it's not supposed to be? But I think I've heard other people say that they have also enounterd B+ on the screws.
Doug

:Hi Doug,
:
:I am curious, do you remember the make/model of radio that had B+ on the adjustment screw of the IF trimmer?
:
:Gary
:

Philco 60 and similar models have B+ on some of the adjustment screws. I wrap a couple of turns of tape around a socket and use it to adjust. I inspect the tape for signs of wear before proceding to the next stage. You will notice that on these radios the adjustment screws which have B+ on them have a small cover that is supposed to be put in place.

I am sure that there are other radios out there with B+ on the screws, too.

In other radios the insulation may have broken down. I have seen sparks on an RCA and a Zenith that I own. Both have floating chassis, so there is no risk of a direct short. I just try to keep the screw driver blade away from the edge to prevent static.

T.

Don't ask me to quote model numbers, but I seem to recall sets where I drew a major B+ spark - between an IF adjustment screw, metal-shaft screwdriver, and the IF xfmr metal can. (Those that didn't knock me down are less memorable.)

:Philco 60 and similar models have B+ on some of the adjustment screws. I wrap a couple of turns of tape around a socket and use it to adjust. I inspect the tape for signs of wear before proceding to the next stage. You will notice that on these radios the adjustment screws which have B+ on them have a small cover that is supposed to be put in place.
:
:I am sure that there are other radios out there with B+ on the screws, too.
:
:In other radios the insulation may have broken down. I have seen sparks on an RCA and a Zenith that I own. Both have floating chassis, so there is no risk of a direct short. I just try to keep the screw driver blade away from the edge to prevent static.
:
:T.

:Hi, when adjusting a primary and secondary screw on a IF Trans are you suppose to use a insulated screwdriver? On some of them when you touch the can while adjusting you get no noise and they adjust just fine. On other ones you get static and all kinds of noise is this normal or is there a short somewhere? Thanks Again, George

George,

Also, I have found that using a metalic screwdriver can actually affect the adjustment. Try an experiment; adjust (peak) the IF with a metal screwdriver, then re-adjust it using a plastic one. You will find that the IF was not at the optimum peak.

Gary

:Hi, when adjusting a primary and secondary screw on a IF Trans are you suppose to use a insulated screwdriver? On some of them when you touch the can while adjusting you get no noise and they adjust just fine. On other ones you get static and all kinds of noise is this normal or is there a short somewhere? Thanks Again, George

Your right a metal screwdriver compared to a plastic does make a difference. So I guess this is normal I was afraid there was a short or something like that. Thanks, George.