Classic Status: Tube premium, 23 channel
Appeal: Dream Rig
Condition: Cosmetic, Good. Electrical, Good
Acquired: 2006, E-Bay
This is my Tram D201, the restoration of which was covered in my "Dream" article. Now that I've completed (as much as I can determine) the restoration, and I've had some time to play with the radio, it's time to review it and compare it to my other classics. First and foremost, I wanted to see if this radio truly is a step or two above the average radio in terms of features and raw performance. Commensurate with this test, is the personal "seat of the pants" subjective test where the radio is pitted against others in terms of the "fun factor" of operating the rig.
The Tram was one of two premium rigs vying for the top spot on the CB king of the hill of equipment. Having a price tag in the $750 - $800 range in the mid 70's, it was a fair chunk of change for the average CB'er so, consequently, not too many people had them. What your money bought you was a rather large rig (It measured over 2 feet wide) outfitted with 15 tubes, 16 (or 19 if you had VOX) transistors and a host of other parts, all easily reachable from a hinged, easily opened top cover. Receiver selectivity was provided by a sharp 6.2 Mhz crystal filter on SSB or a series of resonators or 455 Khz mechanical filters for AM depending on which revision of radio you had. The audio power amplifier/modulator was powered by a 6L6 tube (The same tube found in many guitar amps), which provided strong audio on receive and punchy, authoritative, and warm sounding transmit modulation. Combined with tone controls for both receive and transmit, you could make the rig sound any way you wanted. The radio was equipped with 23 crystal controlled channels, with a fine clarifier which varied frequency about +/- 1 Khz on both transmit and receive. The rig also included a tunable receive VFO which covered the 23 standard channels as well as up to 27.550 for extended receive coverage. One of the most popular aftermarket modifications was to enable this VFO to work on transmit as well, making this rig a favorite for those early pioneering freebanders. Metering for the Tram was provided by a single large meter which showed both receive signal (scaled to +60db over S9), as well as transmit power and SWR.
The Tram was considered a "dream rig" due to its excessive cost (which meant that it was unlikely that I could afford one back then) and premium features, so expectations were high when I first brought it back to life. It should be noted however, that even though I did a good job of bringing the rig back from the dead, I did not replace all the parts (that would not be economically viable), so some of its current performance characteristics may be affected by the age of the components. Judging from the physical appearance of the PC board, this rig has had a lot of hours on it.
Despite the age issues, the Tram's receiver sensitivity was fantastic. It is easily one of my (if not THE) most sensitive receivers. I could drop the level of my signal generator down to .04 uV before I would lose the signal completely. Adjacent channel rejection was good, although I would not consider it to be head and shoulders above some of the other rigs I've tested, and the numbers will bear this out. But adjacent channel selectivity is only one component of the total bleed over equation. Having a tube front end most likely means that front end overload immunity will be better than most although I do not have another generator to measure this accurately. And with so many people running overmodulated radios with class "C" amplifiers, no amount of filtering will reject on-channel splatter.
On the transmit side, the rig really shined. With the power set at 3 watts, the audio was strong and loud with forward moving modulation (swing). The quality of the audio was very pleasing on both AM and SSB. Spectral purity was about average for a 1970's rig, with no major spurs extending above -45dbc (The FCC spec at the time).
Ok, now for the post alignment performance numbers: (My own measurements, not the manufacturer's claims):
Sensitivity: .1uV (.07uV SSB) for 10db S+N/N.
Adjacent channel selectivity: 70db @ 10Khz.
I.F. Frequencies: 6.2 Mhz SSB
455 Khz AM
AM Power: 3 watts.
SSB Power: 18 watts.
AM Modulation: 100+%, 12 watts peak.
2nd Harmonic suppression: -55dbc.
Other spurious emissions: -55dbc.
Of course, the numbers are rather dry, one-dimensional, and only tell a part of the story. How the rig performs in actual conditions is a better indication, and the following is my subjective opinion of the rig:
The Tram came into the test with very high expectations as a result of its pedigree. Reality has a hard time measuring up against the expectations of a dream rig from way back. But even though the deck was stacked against it, the radio did not disappoint. There were a few negative points, but mostly the Tram lived up to its expectations. The receiver's exceptional sensitivity was noticeable when trying to hear (and understand) those weak stations in the distance. The "tube sound" was warm and pleasant to listen to. The squelch action is very smooth and gradual, with no annoying "pops" or "thunks", which drive me crazy. The "S" meter I originally reported as not being all that linear. But after further receiver work, I now find that the meter is almost as linear as the Hy-Gain 623, which has become my "S" meter measuring standard. The Tram is also fairly adept at rejecting the network interference that pervades my operating position. I was complimented on the quality of the transmit audio from the other locals. AM was warm and punchy, and SSB audio "Sounded like AM". There was very little difference in overall tone quality between the Tram and my Hy-Gain, although the Tram did have more punch if the mic gain was turned to the right a bit.
I did mention that there were a few negatives, and these were not all that big of a deal but were a bit annoying. First off, the "S" meter zero drifts a bit from cold. What usually happens is that the meter pointer will initially sit at about S1 or S2 and then gradually move back toward zero as the rig warms up for about an hour or so. When I replaced the associated tubes with new parts, the problem improved considerably, but not completely eliminated. Since I'm admittedly somewhat "S meter centric" and pay way too much attention to signals, it's probably more of an issue for me than for the average guy. I also did not like the operation of the receiver tone control. Usually most tone controls attenuate the high frequency as the control is moved. On the Tram, the low end is attenuated, and the result is a very thin, tinny sound when the control is set to maximum. So I end up setting it to minimum (full fidelity). I also notice that the VFO drifts slightly over time, which makes SSB operation a little bit more work.
All things considered, the rig was a pleasure to operate. The old classics have a certain "soul" or personality that seem to be lacking in a more modern rig. With that in mind, and the reverence that the Tram commanded, it's no wonder that it is one of my favorites. I'd say that there is a very close neck-n-neck race between it and my Hy-Gain for the top spot on my list. Each rig has both pluses and minuses, and neither one is a "perfect" rig in all conditions. I doubt if I'll ever find that "perfect" rig. It's probably too expensive to manufacture in today's climate.......