Click to watch: 
Adding QSK 2500 to unmodified SB220 Amp
Click to watch:
How QSK 2500 meets T/R Relay Timing
Ham Radio QSK (full break-in)
DxConnection:  QSK 2500 Amplifier T/R Switch
   Benefits of  adding QSK 2500 to Your Amplifier
Benefit 1:   QSK 2500 keeps you in sync with the DX station increasing your chances of working it.  
                      (You can always tell  those calling stations not running QSK! )

Benefit 2:   QSK  2500 makes your $800 to $3.5K Amp equivalent to the $7K amp  in pile ups.

Benefit 3:   QSK 2500 reduces the number of times that you have to hear to that loud clunky
                  Amp T/R relay.

Benefit 4:   In rag chews, you can monitor the channel for interference while transmitting.  (Occasionally,
                   you can have the fun of catching the destination station playing with his paddle or key while
                   you are transmitting!)

QSK 2500© Transmit/Receive Switch:

  • NEW!     Use the QSK 2500 for SSB VOX with your amplifier.    (click here).
  • Converts any HF Amplifier to QSK (full break-in) without amplifier modifications
  • Amplifier independent:  Adds QSK to new amplifiers as you upgrade  (no need for QSK in new Amps)
  • Compatible with all HF transceivers supporting QSK (full break-in)
  • RF Power: 2500 Watts  CW/SSB/Data modes at < 1.5:1 VSWR   (1500 Watts at < 2.5:1;  1250 Watts at < 3.0:1 )
  • Duty cycle:  Continuous
  • Acoustically quieted and sealed relays for quiet operation
  • RF losses:  Almost lossless relays (much less than PIN diodes), silver plated SO-239s
  • LED indicators:  Power (green), Transmit (red)
  • Interfaces to amplifier key voltages up to +/-200V  (No additional amplifier interface hardware   required.)
  • User adjustable Amplifier Key delay from 2 sec to 10 sec (factory setting = 3 sec)
  • User selectable key/paddle input delays from 3ms to 16ms (factory setting = 10ms)
  • No hot switching of Amplifier T/R Relay on the first dit or dah of each transmission
  • QSK relays & Amplifier T/R relay protected against hot switching due to transceiver removal of Amp Key signal prior to the decay of transmit RF envelop
  • DC power input:  17 to 25 volts at 200ma (max);  120VAC power adapter (i.e. wall wart) included
  • Very compact enclosure:   5 ¼ in W x 2 in H x 3 in D   (excluding SO-239 connectors)
  • Weight:  < 1 lb
  • Factory option to use the Kenwood transceiver +12VDC Amp Key output
  • 1 year Limited Warranty  (See  QSK 2500 User Manual
  • Introductory Price:     $379  (shipped in the USA)
         PayPal or Credit Card purchase:    Send email to
                                                                          A PayPal invoice will be sent to your email address.
        Check purchase :       Checks will be cleared before shipment.  (Make payable to:  W. Rodgers K3HZP)
             send to:
                                                                       DX Connection                                                                                
                 W. Rodgers  K3HZP                            website:                       
                 5727 Buckfield Court                            phone:   260 432-8223
                 Fort Wayne, IN 46814                           email:

  • QSK 2500© connecting cable set:                              $19.00   (with QSK 2500 order only)


  • 2 each 6’ cables with male phono connectors,
  • 1 each 6’ cable with mini (1/8”) male stereo connectors
  • 1 each mini (1/8”) female stereo to 1/4” male stereo adapter.
  Note:   These cables are for connecting the QSK 2500© to your transceiver and amplifier.  Adapter plugs (not supplied)
                may be required for your particular transceiver or amplifier.            

QSK 2500©  (back view)

RF delay
5ms (min)
8ms (min)
total T/R actuation time(1)
15ms (min)
18ms (min)
longer settings in Xcvr
“          “        “      “
fixed in Xcvr
“       “      “
“       “      “
“       “      “
“       “      “
   “       “      "   
“       “      “
“       “      “
         (1)  Amplifier T/R relay actuation times ‘typically’ range from 13ms to 15ms.
         (2)  QSK 2500© key/paddle output delay selectable range is 3ms to 16ms.  Factory setting is 10ms.
Table 1:  Time available for actuation of Amp T/R relay
  Yaesu FT-1000MP MKV
  Elecraft K3
  Kenwood TS-480, TS-590S,
                    TS-590SG, TS-2000
  Icom IC-7000
  Yaesu FTDX-9000, FT-2000
  TenTec Omni VII & Orion I/II
  Ten Tec Eagle
  ICOM  IC-706 MKIIg
  ICOM  IC-735
QSK 2500©
key delay(2)
(factory setting)