Harbach Electronics PS-220 User Manual

PS-220 PARASITIC SUPPRESSOR KIT INSTALLATION INSTRUCTIONS

PARTS S UPPLIED WIT H THIS KIT:

(2) Plate/Resistor Choke Assemblies (4) #6 Lock Washers (1 Extra) (1) Tuning Capacitor Feed Suppressor (4) 820pF 500V Ceram ic Disc Capacitors (2) 10Ω 2W Metal Film Resisto rs (2) 27Ω ½W Resistors (2) 0.01µF 1KV Ceramic Disc Cap acito rs

To start the installation, read these instructions very carefully. Now unplug the amplifier and remove any input, output and control cables that may be connected to the back of the amplifier. Place the amplifier on a book, front panel up, and remove the bottom screws holding th e feet and case in place. Lift the case up and remove it from the amplifier. Place the amplifier on the bench with the front panel facing you. You are now ready to proceed with the installation.

( ) Remove the 15 sheet metal screws that hold the perforated cover in place and remove this

along with the to p rear plate co ver.

( ) Remove the tubes and remove the plate caps from the tubes.

( ) Remove and save the screw that connects the flexible braid from the HV terminal of the

plate choke to the doorknob c apacitor mount ed on the e nd pla te of the tun ing capac itor.

( ) Carefully unsolder and disc ard the braid from the HV termina l on the plate choke, a s well as

the 2 “paras itic suppres sors”. C lean out the out er hole in the s older lug o f the HV terminal.

( ) Put the plate caps back on the tubes. Tighten securely and reinstall the tubes.

( ) Locate the pec uliar wire, th e on e with a straight wire paralleling a coil. Slip the loop of this

wire over the screw removed from the doorknob capacitor and then put on a #6 lock

washer. Screw this assembly into the doorknob capacitor. Make sure th e suppres sor w ire

is approximately lined up with the HV terminal of the plate choke.

( ) Fish the free end of this assembly through the outermost hole in the HV terminal of the

plate choke. Trim the lead to about 1/8” protruding.

( ) Slip the loop end of one o f the paras itic choke/resisto r assem blies over on e of th e plate cap

scr ews with the coil up, followed by a #6 lock washer. Install this assembly on one of the

plate caps with the assembly pointing toward the HV lug.

( ) Fish the free end of this assembly through the outer hole in the HV lug and trim the end to

about 1/8”.

( ) In a like m anne r, inst all the other p arasitic cho ke/resistor assembly onto the other plate cap,

trimm ing the end t o 1/8”.

( ) Now solder the 3 wires going through the HV terminal of the plate choke.

( ) Turn the amplifier upside down with the front panel facing you.

( ) 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/capac itor 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 term inal strip where you just removed the cap acito r.

( ) Install 1 lead of each of the 0.01µF 1KV disc capacitors through the terminal you just

cleaned. Have the body of th e capac itors about 3 /8” from the te rminal with the c apac itors

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 bod y 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 0.01µ F 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 0.01 mF 1KV c apacitor 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 perforate d cov er and top rear plate cov er. Reinstall the 15 s heet 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 am plifier 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

(419) 945-2359

htt p://www.harbachelect ronics.com

info@harbachelect roni cs. com