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Identifying The Drake TR-7 Differences and Versions

by: Ronald Baker / WB4HFN

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TR-7A Production Changes

What are the production differences between the original Drake TR-7 Transceiver and the later production of the TR-7A?      Between the TR-7 and the TR-7A there were basically five circuit changes.   Along with the circuit changes the only physical differences were the front panel (see page two for details) and the labeling of a rear panel connector.  The circuit changes include:

  1. A noise blanker (NB-7) has been installed.

  2. A 500Hz filter (SL-500) has been installed in selectivity position "A"

  3. Selectivity "B" has been adapted to provide a bandwidth of 9kHz for AM reception.

  4. A surge protection device has been added to the receive antenna input to provide additional protection from static discharges from lightning.

  5. The unused phono style tip-jack on the rear panel has been labeled "TX", and now provides an alternate audio input to the transmitter for sources other than microphone.  This jack is connected in parallel with pin 1 on the front panel microphone jack.    See below the pictures showing the connector labeling on the TR-7A rear panel.

Here again you need to be cautious if you suspect a TR-7 identity issue.  Someone could easily use black rub-on lettering for the transmit audio connector creating a look-alike TR-7A rear panel.

Other Noteworthy Items:

Here are a few other bits of information I uncovered during my research.  Drake no longer has any records of how many TR-7 transceivers were manufactured.  The best we can determine Drake built around 10,500 TR-7's and around 2500 TR-7A's.   We know the TR-7A production started with a serial numbering around the high 10,800's range, and the highest TR-7A serial number I've seen or heard about is serial number 12269.

Some of you may have seen the TR-7 transceiver cabinets in black.   Drake never built a TR-7 or TR-7A using a black cabinet.   The Drake cabinets were either the early version gray sometimes referred to as the "sticky paint" cabinet, or the later version dark gray hard vinyl clad aluminum cabinet.   So where did the black case come from?   As I understand the story, the black case was available from Drake after they stopped manufacturing amateur radio equipment.   After that time Drake was still receiving many orders for replacement cases, so Drake had a quantity of them reproduced as replacement parts and sold them as such for several years until they ceased providing spare parts and support for all the Amateur Radio equipment.   But why a black case?  During that time Drake's cabinet manufacturer was producing black cases for other Drake products including the TR-270 and several of their short wave radios, so Drake decided to use the same material because it was readily available.

The original "sticky paint" case used a new type of paint that would resist scratches.  The only problem was after a while the paint started to break-down, causing the surface to become tacky or sticky to the touch.  As time went on the cabinet paint started to deteriorate and discolored creating a fairly ugly case.  Fortunately, after producing around 2000 TR-7's with this style case, Drake changed to the more popular textured dark gray vinyl clad aluminum case.

Did Drake perform TR-7 to the TR-7A upgrades?   Yes, for a fee Drake did offer to upgrade the TR-7 to the later TR-7A version.  What Drake did was to upgrade the circuitry and internal wiring but did not change the outward appearance of the radio.  Specifically,  Drake did not change the front panel top strip which shows the model number.


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