Drake TR-4 Page


     This page is dedicated to the TR-4 series of Drake HF transceivers. The purpose of this page is to display and describe the differences between the various forms this transceiver took over its years of production.  This page will constantly be under construction as I add new material and make corrections. Some liberties were taken with SN's, its impossible to be exact. I have tried to be as accurate as possible with information shared here but if anyone has any addition information or corrections to share please email me at gpoland1@cinci.rr.com
    Special thanks to WD8DFP Bill Frost of R L Drake and
K4OAH Garey Barrell for their assistance with this page.

The TR-4


    This the earliest of the TR-4's and began production in 1965. The first TR-4's were essentially TR-3's with new front panels. Serial numbers range approximately from 16000 to 19443. The earliest TR-4's shared the same Tedford " soup can " filter as the TR-3. This 4 pole filter was made up of  8 crystals soldered to a wafer switch and mounted in a metal can. In December  of 1965 with SN 19444 the Tedford filter was replaced with a 4 pole filter which had both the LSB and USB filter in one sealed container.  Also transmit mixer tube V4 was changed from a 6HS6 to a 6EJ7.

       soupcan_inside                                            tr4_bot_soupcan
        Soup Can filter with                                        Bottom of early TR-4
           shield removed.                                            with  Soup Can filter.

                    Tyco 4 pole  LSB/USB filter.                  

    In the early TR-4 if a noise blanker was desired it was hard wired in. Originally it was offered as a kit but later only as a factory installed option. The 34-NB blanker was a copy of the TR-6's 9-NB and did not have a plug nor was there a BLANKER  switch in the front panel. The 34-NB was turned on and off with the addition of a switch behind the PLATE tune knob. Later Drake installed the noise blanker switch in the right bottom corner ( standard location ) with a decal applied as a factory modification. 

NB_sw          tr4 hard wired nb
         Noise blanker switch.                          Hard wired 34-NB and switch.


    In December of 1966 more changes were made to the TR-4. Beginning with SN 26000 Receive IF tube V11 was changed to a 12BZ6 from a 12BA6. Balance modulator diodes where changed from 1N270's to 1N514's.  The single LSB / USB 4 pole filter was replaced with two separate 8 pole filters; one for USB and another for LSB.  Early filters were gray.  Later blue filters from TYCO were used.


   8 pole sideband filters


    The first big change in the style of  TR-4 was the addition of a plastic kHz dial pointer
behind the dial skirt of a B-Line style knob that was illuminated by a neon bulb . This bulb would signify which PTO was in use when a RV-4 remote VFO was connected. Production began in late 1967 approximately at SN 27000.  Also around this time the black one piece PA cage was replaced with a chrome two piece cage. Still no NB knob.  In March 1968 with SN 27538 V5 was changed to a 6BA6 and V11 was changed to  6BZ6.


    In 1970 with SN 30500 the TR-4 was offered with a front panel BLANKER switch and noise blanker socket.  The  34-PNB was made available as a plug in option. Also the audio output section got an upgrade with the addition of a transistor pre amp ahead of the 6AQ5 audio output tube.
1970 34NB Add

The TR-4C
Serial Numbers were collected from actual transceivers and are not complete


TR-4C    March 1973 SN 34000 to  SN 42634
April 1976  6EV7 changed to 6FQ7  and T/R relay changed to 2500 Ohm.
Chassis was no longer copper plated.  Addition of a second dial for kHz.
Plug in T/R relay. Tuning knob and dial skirt style changed.


TR-4CW   November 1976 SN 42719 to 43933
500 Hz 6 pole CW filter added


TR-4CW/RIT April 1977 SN 44026 to 45434
 RIT circuit added

To Be Continued..........................