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Date Posted by Category User IP

2015-09-03 (UTC)


HF Amplifiers

Heathkit SB-220 2000 watt input HF amplifier $650

Restored and upgraded with new circuitry over weeks of careful labor. Puts out great power with healthy 3-500Z tubes. Original front panel with no added holes or scratches. CDROM with manual and files on modifications, etc. Documentation and receipts provided on added circuitry. Top cover repainted. Some bending of left rear of chassis due to shipping, but front panel and case panels were not affected. Inquire if you want to buy my 3-500Z spare tubes. For inexpensive companion full legal power Ameritron antenna tuner, see auction ???
Upgrades and rebuilding:
All new, computer-grade 105 degree F plate supply filter capacitor bank (8 each 560 uF @ 450V) with extra capacitance for longer, more powerful peaks
New bleeder resistors on the plate capacitors with less heat that wastes power and heats up nearby components
Outboard standby toggle switch to bypass amp even when it’s on
Low voltage T/R switching compatible with modern rigs, using the Softkey kit from Harbach Electronics
Step start circuit to de-stress power supply components, using heavy duty solid state relays
Improved parasitic suppression networks using the kit from Richard Measures, AG6K, using nichrome inductors, silver solder, etc.
Dual speed fan timer runs fan on slow speed when not transmitting, for much less noise
Heavier duty +120 supply with bridge rectifier and bigger 100uF capacitor for 3-500Z bias and added circuitry
Thermal breaker on power transformer inhibits transmit if transformer threatens to get too hot
Heavy duty diodes protect meters from “glitches” and parasitics
LED panel lights in meters will never need replacing
Shock mounting for fan for less vibration and noise
MOVs protect 120/240 VAC power input
Wired for 240 VAC but can be changed to 120 VAC
Plate tuning capacitor edges smoothed to prevent arcing
$650. Paypal or advance check accepted. Local pickup only
Call Rick KI6LQL to inquire further: 831-662-0507

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