Any Tram D201 that did NOT include 455KHz ceramic filter?

[capn357]

Does anyone know of either a Tram D201 (23 channel) design variant or modification that did NOT include the 455 KHz ceramic filter components (i.e. X400,X401,X402,X403,C445,C446,C447) as shown on the attached receiver board layout?

I purchased an old Tram from Ebay that does NOT have these components on the receiver board (see attached photo), but the board really doesn't show obvious evidence of these parts being removed (like solder joints with holes in them on bottom side of board) so I am wondering if maybe it is legit and not just a robbed unit.

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[Sandbagger]

Feb 13, 2017 7:04:13 GMT -5 capn357 said:

Does anyone know of either a Tram D201 (23 channel) design variant or modification that did NOT include the 455 KHz ceramic filter components (i.e. X400,X401,X402,X403,C445,C446,C447) as shown on the attached receiver board layout?

I purchased an old Tram from Ebay that does NOT have these components on the receiver board (see attached photo), but the board really doesn't show obvious evidence of these parts being removed (like solder joints with holes in them on bottom side of board) so I am wondering if maybe it is legit and not just a robbed unit.

Yes, Tram updated their design. Those components (X400,401,402,403) were ceramic resonators,used in the hard wire versions. In the newer design (Right before the D201A came out), they switched to a pair of 455 Khz filters. Fewer components and I'm sure it was cheaper too.

[capn357]

Thanks.

[2600]

The transition from the old round resonators with two pins to the square black filter with three pins was gradual. The original open-chassis (hand-wire) D201 had four of the roundies on a small pc board. The early circuit-board 23-channel D201 had four of them on the large receiver board. Saw a few with only two of those, and a single black square filter near the relay. The 40-channel D201A was built with just two of the square black filters. Don't see too many of the "half-and-half" radios. They were all the 23-channel model.

In the early 80s, all original Tram parts came from L.C. Maynard's Maycom in Stevensville, MI. He had bought them all from a company called "Satellink" who took it over when Tram closed. They said the round filters were discontinued and would sell you a pair of the black square Murata 3-pin filters with a photocopied instruction sheet to convert the radio to use them.

And that's what we have been using for about 30 years, once I found more-affordable sources of the black Murata filters.

The production of the radio in this detail didn't so much "switch over" as it evolved.

73

[KneeBiter]

2600 Would you have a copy of that mod from round to murata that you could send me?

[2600]

Alas, my paper library has suffered from neglect since the info I use most often is in the computers here.

That stuff never got scanned, that I know. I'll see if I can find it and get a pic that's readable.

73