MagneQuest PGP 8.1 power transformer installation
In order to keep the cost of the PGP 8.1 transformer as low as possible, and to make it easy for the builder paint the bell end before installation if they desire, the transformer is shipped with the top bell end cover not installed. If the bell end is to be painted, be sure to remove the protective oil coating with a solvent like acetone, or a degreasing cleaner like 409 before applying the paint. Installation of the bell end cover is easy, if done with the application of a solvent to loosen the nuts on the ends of the bolts which hold the laminations and the cover in place.
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First apply a drop of acetone to the nut of each corner of the transformer. Be careful not to use more than a drop or two, as the acetone will soften the varnish finish on the transformer laminations if it slops over onto them. |
| Let the acetone work for a few
seconds, and then carefully loosen the nuts, one by one, using a slotted
tip screw driver of adequate size to avoid damaging the screw’s slot,
and an 11/32” socket wrench. Remove the screws using some axial pressure
to keep the screwdriver from skipping from the slot, and keep track of the
order of the placement of the washers as they come off.
NOTE: once the screws are removed, be very careful with the transformer! Damage caused by dropping the transformer and knocking laminations apart is not covered under warrantee !! |
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Next install the bell end and
replace the screws, following the original order of the placement of the
washers. Before tightening snugly, place the transformer into the mounting
holes in the amp chassis to make sure they are properly spaced. Then
remove the transformer and tighten the nuts snugly, but not so tight as to
stress or deform the laminations.
Your PGP 8.1 is now ready to install.
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The terminal identification of the PGP 8.1 is as follows:
1S start of the 700VCT ( a.k.a. 350-0-350V) 75 mA secondary winding
1T 700VCT secondary center tap
1F finish of the 700VCT secondary winding
2S start of the 115V primary winding
2F finish of the 115V primary winding
3S start of the 6.3V 2A secondary winding
3F finish of the 6.3V secondary winding
4S start of the first 2.5V 1.25A secondary winding
4F finish of the first 2.5V secondary winding
5S start of the second 2.5V 1.25A secondary winding
5F finish of the second 2.5V 1.25A secondary winding
For a 2A3, 45, or other 2.5V filament connect 4S to 5S and connect 4F to 5F for a 2.5V 2.5A filament supply. Connect one end of the tube filament to 4S and 5S, connect the other end of the filament to 4F and 5F.
For a 300B first connect 4F to 5S, and then connect one end of the tube filament to 4S and the other end to 5F for a 5V 1.25A filament supply