Sandbagger
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Post by Sandbagger on Jan 27, 2009 8:40:47 GMT -5
I have recently acquired a vintage Tram Titan (the original AM-only version). It's in fairly good condition, and receives and transmits. The main problem it has is a background hum in the speaker. It does not vary with the volume and is not present in the transmit audio. Filter caps are ok, and I get less than 1 volt of ripple on the HV supply. I suspect that it's some sort of ground loop around the audio driver tube (If I pull it, the hum disappears and the tube is fairly microphonic as well). But here's where the real enigma comes into play. I picked up a SAMS book for it (#13), but when I look at it, it didn't take me long to discover that the schematic does not agree with the radio. The SAMS schematic calls for a 12AX7 audio driver tube, while my radio uses a 6BR8 (which is not pin compatible with a 12AX7). The pin wiring appears factory, so I'm wondering if Tram had an "early production" / "late production" situation here, or is the SAMS just wrong?
I'm thinking mine may be the later version since it closer resembles the circuitry of the Titan IIa that I also have.
So if any Tram historians know the story here, I'm curious to know, just to satisfy my curiousity.
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Deleted
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Post by Deleted on Jan 27, 2009 17:24:14 GMT -5
I have the same problem with the RCA Co-Pilot, and I replaced all the caps. And that unit is a solid state. I originally bypassed the internal power supply, and the noise went away, so I replaced the rectifiers, and it worked for a while. Then it came back. Bypassed the power supply again, but no dice. This is the radio with the terrible audio reports. I made this look fantastic after it looked like hell, only to have it fail. It is scrap now.
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Post by spitfire441 on Jan 28, 2009 6:55:03 GMT -5
Adding to the enigma is my Titan is different than Sanbaggers. Here is the tubes found in mine. How does it jive with the Sams?  |
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Post by Junior on Jan 28, 2009 9:10:55 GMT -5
I will look at mine today and see how it compares. I have a handful of crystals missing from mine, and need to know which ones go in which positions. Can you look at yours and make me a map? I would really appreciate any help. Boy, that sure is a clean chassis. Wish mine looked that good.
JR
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Sandbagger
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Post by Sandbagger on Jan 28, 2009 11:26:48 GMT -5
Adding to the enigma is my Titan is different than Sanbaggers. Here is the tubes found in mine. How does it jive with the Sams? With the exception of the 12AT7 in place of a 12AX7 (they will sub on some occasions, although not a direct replacement), yours agrees with the SAMS. Mine is the odd man out, I have a 6BR8 where you have the 12AT7, and those tubes are nowhere near the same. I'm thinking that mine may be a newer revision since it is more like the Titan IIa, but I can't say for sure...... Love a good mystery though........ |
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Post by spitfire441 on Jan 28, 2009 17:01:21 GMT -5
Should I put a 12AX7 back in place then where the 12AT7 is then? I have spares. I would rather I be closer to original, if that would be original.
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Post by crazybob on Feb 24, 2009 17:21:19 GMT -5
My Tram Titan AM only radio has a 6GM5, instead of the 6GK6. It doesn't have the xtal socket on the front either.
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Sandbagger
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Post by Sandbagger on Feb 24, 2009 18:11:24 GMT -5
My Tram Titan AM only radio has a 6GM5, instead of the 6GK6. It doesn't have the xtal socket on the front either. Holy heck! What's the serial number Bob? You might have an even older version..... |
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Post by crazybob on Feb 24, 2009 19:22:53 GMT -5
The serial # is 6297.
About 9-10 years, I sold a green-faced TR 27 (no A, B, C, E, designation) base on ebay to a collector called "radio walt". The serial # on that radio was 26.
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Sandbagger
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Post by Sandbagger on Feb 25, 2009 9:17:51 GMT -5
The serial # is 6297.About 9-10 years, I sold a green-faced TR 27 (no A, B, C, E, designation) base on ebay to a collector called "radio walt". The serial # on that radio was 26. Looks like your Titan is even newer than mine. My serial number is in the 3000's. Spitfire's is older. It would seem that Tram made several changes to that radio during its production run. By the time the Titan II came out the Xtal socket was missing as well. I guess it wasn't a big selling point. |
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Post by crazybob on Feb 25, 2009 17:15:57 GMT -5
I think that it was a receive crystal socket. The Titan II's, & my Titan have it under the chassis.
Hey... which tube or tubes could I change to get the AGC to work better? ..Nearby, strong stations over load me. Otherwise, My Tram Titan is one of my favorite radios!
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Post by spitfire441 on Feb 26, 2009 1:46:27 GMT -5
My Tram Titan AM only radio has a 6GM5, instead of the 6GK6. It doesn't have the xtal socket on the front either. I think I have an old Titan, Ser# 2623, and I have a 12ax7 where you guys have a 6xxx toobe. I have the Xtal socket for RX. |
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Sandbagger
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Post by Sandbagger on Feb 26, 2009 9:19:43 GMT -5
I think that it was a receive crystal socket. The Titan II's, & my Titan have it under the chassis. Hey... which tube or tubes could I change to get the AGC to work better? ..Nearby, strong stations over load me. Otherwise, My Tram Titan is one of my favorite radios! I haven't seen an overload issue on mine yet. So far no one has been close enough to overload me. Unless this is a well know "design issue", it's possible that your radio has an AGC problem. Even if it is a design problem, it's also not going to be a matter of simply swapping tubes to correct it either. There will have to be other circuit changes as well. Looking at a later model radio might lend a clue to any design changes they may have made. The tube changes that I've seen on the Titan though, have nothing to do with the receiver, rather the audio section. The Xtal socket was indeed for the receiver. I guess the idea was to get a "rock" for your home channel and use that so that you didn't have to worry about the tuner drifting off and you'd have instant access. |
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Post by Junior on Feb 26, 2009 17:27:52 GMT -5
Just checked my Titan, and it is number 2946.
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Sandbagger
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Post by Sandbagger on Feb 26, 2009 18:53:56 GMT -5
Just checked my Titan, and it is number 2946. Which tube do you have for an audio driver, the 12AX7 or the 6BR8? |
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Post by Junior on Feb 26, 2009 20:16:10 GMT -5
12AX7.
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Sandbagger
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Post by Sandbagger on Feb 27, 2009 12:50:17 GMT -5
Then yours is the "older" revision as well. Mine is 3072, and I wonder if they made the V9 tube changeover starting at serial number 3000......... |
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