NE7X - Henry 2K QSK Upgrade New Page 1

Henry 2K

TR QSK Upgrade

 By: NE7X - 05/01/2011



Replace the slower mechanical T/R relay in the Henry 2K with high speed Gigavac model GH1 and GH3 (datasheet) 5KW 6ms 26VDC SPDT vacuum relays.


Two GH1 (RF) and One GH3 (HV-BIAS)


To accomplish sequencing for the vacuum relays, add a JWM Engineering Group  four step port programmable SEQ-QSK T/R Sequencer.




RF Deck Removal

Remove AC power

Remove top RF deck cover

Remove 3-400 tubes and chimes

Remove chassis power supply bottom front cover

 From inside bottom power supply, disconnect HV cable and 8 pin octal plug from top RF deck

From inside bottom power supply, disconnect fan & AC cables attached to two feed through capacitors going to the top RF deck

 From inside the RF deck, along the outer edge, remove nine (9) sheet-metal screws

Remove three (3) screws on chassis rear, next to RF coax connectors

Lift the RF deck off the power supply pedestal

With RF deck up-side-down, remove the bottom RF deck cover


Henry 2K RF deck (upside down) on workbench with bottom RF cover removed




Original Mechanical TR Relay




Original Mechanical TR Relay Removed



Original Mechanical TR Relay and mounting Plate

Remove the relay from mounting plate


Original Mechanical TR Relay Plate

Re-Use to mount Vacuum Relays - Make three 5/8 inch (18mm) Holes



Vacuum Relay Wiring Diagram


Mount Vacuum Relays and Wire

Install four new rubber grommets (optional to reduce noise vibration)



Mount Vacuum Relay in Location of Original Mechanical Relay


Top View of Vacuum Relays Mounted

Route wires to rear of chassis



Wire Vacuum Relays to SEQ-QSK

Relays are +26VDC and SEQ-QSK Sequencer is +12VDC

Use LM7812 to reduce the +26V to +12V for the SEQ-QSK




Mount the LM7812 and SEQ-QSK to the bottom cover of the top RF deck





LM7812, two .01uF caps and SEQ-QSK Sequencer




Reassemble the top RF deck to the power supply pedestal. Reference the RF deck removal procedure in this document, perform steps in reverse order.




Connect HV plug, 8 pin octal plug, FAN and AC power wires to top RF deck feed through capacitors.

View of LM7812, two .01uF caps and SEQ-QSK Sequencer after RF deck has been reinstalled.



The internal +26VDC power supply in the Henry 2K is not regulated. When the +26V HV Mercury Relay is engaged, the +26V supply drops to approximately +18V. This is low to reliably power the vacuum relays. Add a +24VDC computer laptop AC power supply to the bottom power supply deck.   



Note the two yellow wires

Top yellow wire goes to HV Mercury Relay

Bottom yellow wire goes to vacuum TR relays and SEQ-QSK (pin #4 of 8 pin octal plug)

The laptop 120VAC adapter leads are the two back wires, bottom right/left lugs.





Rear of the Henry 2K, optional Inhibit Loopback RCA plug added

(This is SEQ-QSK S4 output)



SEQ-QSK Programming

  Power off the amplifier

 Remove bottom front power supply cover

Add jumpers to pins 1<=>6 as described in the SEQ-QSK programming manual

Replace bottom front power supply cover

  Power on FILAMENT power switch, wait 10 seconds

Power on PLATE power switch, wait 10 seconds

Power off PLATE and then FILAMENT power switches

Remove bottom front power supply cover

Remove ALL jumpers from the SEQ-QSK

   Replace bottom front power supply cover



Henry RF Amplifier Information Center Web Site

Additional Information about other Henry RF Amplifiers

Modifications & Upgrades


Happy QSKing

 NE7X Web Site


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