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Identifying The Drake TR-7 Differences and Versions
by: Ronald Baker / WB4HFN
The Identity Question
Over the last few months there has been discussion around the Drake TR-7, what are the actual differences and how can you determine which version you really have. In recent months we have seen TR-7's for sale described as the later TR-7A version or upgraded to the TR-7A version. In some cases a front view photo of the radio appeared to actually be the "A" version, but to be revealed in other photo's that it wasn't truly the case. Need we be concerned about the possibility of counterfeit TR-7 transceivers on the market? That question I'm not going to address here, but I will give you what information I have discovered through a lot of research to help you determine for yourself that answer. Since Drake manufactured several versions of the same model, for example the Drake R-4 receiver, here we have four versions, R-4, R-4A, R-4B, R-4C, each externally looking very similar if not identical. The same is true for the solid state transceiver, the TR-7 and TR-7A. To make sure the equipment model and versions stayed the same Drake implemented a simple procedure. When you wanted to replace a damaged front panel you shipped your old front panel to the company before they would ship out the replacement panel, ensuring the radio model and version identity remained the same. Today with the advent of after-market products and the availability of new and used parts including front panels being sold over the Internet accurate product identification now becomes a gray area of concern. In this article I will discuss the Drake TR-7 transceiver, identify the best I can the differences between the models and versions within the same model. In my research I have identified three significantly different versions of the TR-7 transceiver. First there are two versions of the original TR-7, which I will classify as the early and late version, and then the last version the TR-7A model. Also, the last three pages of this article discuss the various circuit changes the TR-7 went through is its life time, these include the power amplifier, noise blanker and 2nd IF/Audio board.
The Rear Panel Configuration
First lets identify the external differences in the original TR-7 transceiver. From the front both the early and late versions look identical, the real differences was on the back panel. The early version had a one piece back panel from one side to the other. The late version incorporated a three piece sub-panel construction where a center sub-panel with all the connectors screwed to end panels on either side of the radio. Take a look at the following two pictures identifying both versions.
The change to the late version three piece panel made it much easier to gain access to the wiring side of the connectors over the earlier version. This production change to the three piece rear sub-panel happened somewhere between July 1978 to February 1980, the best I can determine. By serial number, the best I can tell this production change occurred somewhere between 4800 and 4941. The later TR-7A transceiver used the same rear panel configurations as the TR-7 late version. On the rear panel the only difference between the TR-7 and the TR-7A was a wiring change to one of the connectors which is discussed in detail later in this article.