NE7X - Henry 2KD-5 QSK Upgrade

NE7X - Henry 2KD-5 QSK Upgrade New Page 1

Henry 2KD-5

TR QSK Upgrade

By: NE7X - 07/29/2011

This QSK modification replaces the slower mechanical T/R relay in the Henry 2KD-5 with high speed Gigavac model GH1 and GH3 (datasheet) 5KW 6ms 12VDC 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.

PROCEDURE:

Remove all attached cables

Remove AC power

Place amplifier on workbench, on its left side, so the under belly is exposed.

Remove bottom perforated RF shield [nine (9) sheet metal screws] and the solid bottom tube/input circuit cover [seven (7) sheet metal screws].

The mechanical TR relay is located toward the front of the chassis under the HV door knob switch.

Remove the Mechanical TR relay from RF the deck. There are four nuts holding down the relay mounting plate. Cut or unsolder the wires from the relay.

Mechanical TR Relay and mounting plate

Remove the mechanical relay from mounting plate

Make three 5/8 inch (18mm) holes into the relay mounting plate for mounting the vacuum relays.

Vacuum Relay Wiring Diagram

Mount the vacuum relays to relay plate and wire the DC coils as indicated in the above wiring diagram

LEFT=BIAS (GH3) CENTER=RF-IN (GH1) RIGHT=RF-OUT (GH1)

Mount the vacuum relays/plate in the same location of the original mechanical relay using four metal stand-offs which allow for proper clearance. Once the relays are securely mounted, wire the vacuum relay contacts for RF-OUT, RF-IN and BIAS. (reference 2KD-5 schematic or diagram below)

At this time you can mount an optional TVS (transient voltage suppressor) diode across the +12VDC input on the SEQ-QSK. The TVS will provide very fast responding when handling transient power spikes up to 1500 watt power. Considering the arc is a very fast and short duration phenomena, a TVS could possible prevent a failure of the SEQ-QSK.

http://Mouser.com sells them for $0.59 each in single qty. They break down at around 18 volts which would be a good voltage to stop any over-voltage. The regulator on the SEQ-QSK is rated at 30 volts maximum input, so 18 would be a good level.

The Mouser part number is: 863-1.5KE18AG

Mount the TVS directly on the SEQ-QSK board by soldering the cathode lead into the +12 volt hole and the anode lead to the closest ground hole. It is important to keep the leads of the TVS as short as possible as the inductance of the lead length can cause an overshoot. And the overshoot is what you want to suppress, not make worse. Leave enough TVS lead from the +12 volt hole to allow you to attach the +12 volt line to it.

Drill four (4) holes and mount the SEQ-QSK on stand-offs to the tube/input circuit solid cover plate. Solder all wires to SEQ-QSK coming from vacuum relays (see wiring diagram below)

Install both the bottom tube/input circuit solid cover plate with the SEQ-QSK mounted to it, and the perforated RF shield. Cut a notch in the RF shield to allow the vacuum relay wire to come through. Secure both covers with sheet metal screws.

SEQ-QSK Programming

Power off the amplifier

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

Power on amplifier, wait 10 seconds

Power off the amplifier

Remove ALL jumpers from the SEQ-QSK

Henry RF Amplifier Information Center Web Site

Additional Information about other Henry RF Amplifiers

Modifications & Upgrades

Happy QSKing

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