User Guide

2
( ) Locate the (2) 1mH chokes going from the rear-most tube socket pin. Remove each of
these chokes. Clean out the hole through which the chokes were removed.
( ) In place of these chokes, install a 27Ω resistor paralleled with one 820pF disc capacitor (1
resistor/capacitor pair for each choke).
( ) On the right hand tube socket, parallel the existing 200pF capacitor closest to the front
panel with (1) 820pF disc capacitor. Leave all other 200pF capacitors in place.
( ) On the left hand tube socket, parallel the 200pF capacitor on the extreme left with the
remaining 820pF disc capacitor. Leave all other 200pF capacitors in place.
( ) Locate the 2-lug terminal strip just behind the filament choke (the input drive coax is
connected here). Remove the capacitor going from this strip to the filament wires. Clean
solder from the terminal strip where you just removed the capacitor.
( ) Install 1 lead of each of the 0.01µF 1KV disc capacitors through the terminal you just
cleaned. Have the body of the capacitors about 3/8” from the terminal with the capacitors
lying flat and pointing to the left.
( ) Take (1) 10Ω 2W resistor and wrap a lead around the closest filament jumper connection
(the one going between the tube sockets). Place the body of the resistor about 3/8” from
the filament jumper lead. Solder and trim any excess lead.
( ) Connect the free end of this resistor to the undermost 0.01µF 1KV capacitor lead. Twist
these leads together and solder. Trim any excess leads.
( ) In a like manner, install the second 10Ω 2W resistor onto the other filament jumper lead,
spacing the body about 3/8” from the jumper.
( ) Connect the free lead of this resistor to the uppermost 0.01mF 1KV capacitor lead. Twist
these leads together and solder. Trim any excess leads.
( ) Space all components so that there is at least 1/8” between any 2 wires or components.
Sight across the bottom of the amplifier to be sure that there is plenty of clearance between
the components you just installed and where the case will soon fit. Adjust as needed.
( ) Replace the perforated cover and top rear plate cover. Reinstall the 15 sheet metal screws
holding these pieces in place. DO NOT over tighten these screws, as it is fairly easy to
strip the screw threads in the aluminum underneath.
( ) Use the book to hold the amplifier while you reinstall the case and feet..
This completes the installation of the PS-220 Parasitic Suppressor kit. You will find that
your amplifier tunes much more smoothly than before and there will be no more arcing or spitting
on voice peaks.
HARBACH ELECTRONICS
Jeff Weinberg – W8CQ
468 County Road 620
Polk, OH 44866-9711
[phone]
http://www.harbachelectronics.com
[e-mail]