In most of my dealings with TR-3's, I have found that the parts that are in common with the two (except the finals) are identical.? From a manufacturing standpoint, it makes much sense: why spec completely new / different parts when the existing ones work fine?? Yes, there can be differences (the PTO, 12JB6 vs 6JB6) but the other parts should be the same.
There was a previous question about swapping relays and I'm not sure about that one because the TR-4 switches a MUTE and an EXT RCVR that the TR-3 doesn't.? Trust but verify.? (BTW, if you find that the relay is the same or different, for sure, please let the group know for posterity).
Main differences, functionally, are several:
- 12JB6 vs 6JB6 finals
- Tube vs solid state PTO
- Addition of the switching, connectors and side switch for use with external receiver
- Sidetone
- PA cage -- open vs. closed
- tube variations.
I would be comfortable with the RF chokes being identical, along with probably 98+% of the parts that are in common.? The tube lineup from the TR-3 to the TR-4Cw RIT is amazingly stable from 1963 to 1978.? The overall design is even more stable.
73,
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
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On Thursday, March 27th, 2025 at 12:48 AM, Steve KL7JT via groups.io <radiorobots@...> wrote:
Are there any dimensional or other differences?
?
Thanks for any experiential comments.
