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Post by capn357 on Feb 25, 2017 13:11:11 GMT -5
I've been watching a D201A for sale on Ebay. The auction started with a bid threshold of $400 and a buy-it-now price of $600. The unit looks pretty cherry and comes with the original manuals, original box, and original invoice. Had it included the grey channel selector, I would've considered dumping $600 to buy it outright. However, it clearly has the old black AMP channel selector and the listing description mentions that there is some static when changing channels, so I begged off. Anyway, the auction sat for days with no bids at all, but then all Hell broke loose. It's now at $810 with one more day to go!
The market for this old vintage stuff on Ebay really fascinates me. For example,
A Pioneer SX-1980 receiver that originally sold for ~$1,400 in the late seventies now brings between $2,000 and $3,500 depending on condition. A Tram D201 CB that originally sold for ~$700 in the mid to late seventies now brings between $150-$400 (not counting the crazy one I just mentioned) depending on condition. An HP 8568B spectrum analyzer that originally sold for ~$30K in the mid eighties (and is built like a freakin tank) brings between $500 to $1,000 (if they sell at all).
I guess there is just no market for an 100 lb, two box spectrum analyzer no matter how good it is. Plus, despite HP's then reputation for making very robust and bulletproof test equipment, I'm sure many of the components in that unit are unobtainium should anything go wrong.
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Post by capn357 on Feb 25, 2017 11:53:08 GMT -5
Thanks, Sandbagger. That is the manual I downloaded sometime ago that covers the PCB version. I was looking for a version of the manual for the hand-wired unit just in case there might be some significant differences. Should I interpret your reply to indicate that the PCB version of the manual applies to the hand-wired version as well (other than the pictures of the PCB layouts, of course)?
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Post by capn357 on Feb 25, 2017 11:11:05 GMT -5
So I just picked up a hand-wired D201 from Ebay. I probably paid too much for it, but I was anxious to get my hands on one of these. The unit worked fine when it arrived, but of course, I couldn't let well enough be alone and decided to clean the dust out of the inside. Despite my best efforts to be careful, I evidently broke something because now the manual receive is completely dead. Not intermittent, not weak, and not off frequency; it is dead. Crystal side works fine on both receive and transmit.
I've looked for the obvious loose wire that may have resulted from my mucking around in there, but I can't find anything. I also swapped out the tube for V302, but no joy.
Does anyone know where I can obtain a service manual for the hand-wired version? I have the schematic (it came with the unit), but I don't have the service manual. I do have the service manual for the D201A (that's easily found online), but I figure there are obviously some differences between the hand-wired unit and the PCB-based unit.
Update 3/20: After many hours looking here and there, I finally found the issue. There was a short at a terminal panel that effectively shorted out the pin 7 and pin 8 circuits of V302B. Once the short was eliminated, everything on the manual receive (and transmit) functioned just fine. My joy was short-lived, however, as another unrelated audio hum problem surfaced within 10 minutes of the fix. That's the way these old radios are, I suppose.
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Post by capn357 on Feb 22, 2017 23:58:11 GMT -5
Sorry if this has been asked and answered before, but I'm curious to know if any of the PC board based D201's were manufactured in the U.S. or if all of them were manufactured in Mexico. I'll occasionally see an old D201 selling on ebay where the "Assembled in Mexico" label is conspicuously missing from photos of the rear of the unit.
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Post by capn357 on Feb 19, 2017 20:55:12 GMT -5
I'm right there with you on the time capsule. For me I have 4 points in time. The first was early 70's when we all ran walkie-talkies and could actually talk 3 or 4 miles without any trouble because the "fad" hadn't started yet, the sunspot cycle was at the bottom, and the ambient noise was very low. Then, like you, I have the mid-late 70's full on fad period, where the channels were packed with people, the skip was ever-present, bleed over was the biggest nemesis, and everyone was obsessed with obtaining big power and extra channels. Of course back then "big power" was anything over 200 watts. Then there was the 80's into the 90's. It was a time of transition. Export radios hit the scene. The casual fad user lost interest and moved on, and those who were left were more serious radio operators. But the level of civility also dropped, as the language became much more abrasive, and the "CB Rambo" types became much more prevalent. Then we have the 21st century. Radio Shack stops selling CB radios. There are very few places where you can buy them locally. Export and "10 meter" radios outnumber legal CB radios by a wide margin, and most radios are made in China or some Pacific Rim country. Old timers become nostalgic for the "good old days" and start collecting vintage radios which starts inflating their worth (a radio that you couldn't give away at a hamfest in the 80's is now fetching $50 - $100 or more on E-Bay). Yet another sunspot cycle has come and gone, and it was not nearly as strong as the last one, and most of the skip heard was south of the border Spanish speaking stuff (at least for those of us on the East coast). As you've noticed, the amount of noise generated from digital widgets, switching power supplies, LED's, and computer networks makes running mobile an exercise in frustration. And even from the base station, there are devices that cause receiver pain. And I suspect, it's only going to get worse. We now have trains being fitted with speed control systems which transmit on channel 13, and put out spurs on several other channels. The FCC doesn't seem to be all that interested in it, and I'd bet they're secretly happy about it, since they'd like nothing more than to have the CB band go away. No kidding about the inflated prices for old radios! i won't call out the manufacturers here, but stuff that was considered to be junk or marginal back in the day is now suddenly sought after for some reason. As far as the new lack of civility goes, I've already noticed that here in the last few weeks. Admittedly we had our drunks and general pain in the butts back in the 70's, but there were enough people in the CB community listening at any given time that would intervene and keep that pretty well under control. Moreover, the small town i grew up in (not so small now) made it much tougher to be an anonymous jackass on the air.
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Post by capn357 on Feb 19, 2017 20:41:50 GMT -5
I have an easy reduce power mod for you. Buy a 2E26 tube, it will directly replace a 6146. Its good for about 18 to 30 watts peak, depending on plate voltage. I did this to my Multi Elmac transmitter as the 6146 was too much power to drive my 8 pill. The 2E26 is perfect. BTW the Elmac uses a pair of 5881 tubes in "shove yank", they are industrial equivalent to 6L6 Great, thanks! Do you have any recommendation on which 2E26 manufacturer(s) are good (or alternatively, which manufacturer(s) I should avoid)?
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Post by capn357 on Feb 19, 2017 8:29:59 GMT -5
I can also relate to living "in a hole". I did that for the first 29 years of my CB experience. I lived in a creek valley and 3 out of the 4 major directions, my signal had to climb hills to get out. Only to the SW did I have a shot that didn't run right into the side of a hill. I didn't do too badly for where I was, or at least I didn't think so compared to the other locals who lived in the area. You don't realize how much you're missing out until you move to a better area. Towers, big beams and some extra power help to make up for the shortfall in signal level. But living in the hole is a 2 way street and if you can't hear them, you can't talk to them either. Hopefully you have a decent group of locals where you live, or you'll lose interest in CB real quickly. Skip is hit or miss, and right now we're just about to the bottom of the sunspot cycle, so the chances of good F layer skip is just about nil for the next 6 or 7 years. E-layer skip will hit again in the early summer months, but then that will fade away until next January or so. You'll get sporadic hits of it here and there but nothing predictable. Acknowledged. Just from the monitoring I've done here over the past few weeks, I have heard a fair amount of skip roll in (seems like at least once a day), and I'm getting plenty of signal from some of these guys that I'm sure are running impressive power. When it comes to the CB airwave experience, I'm the guy who's been buried in a time capsule. I can speak to three points in time: 1. Mid to late seventies where everybody and his brother had one of these things plus high sunspot activity = S9 baseline noise on every channel. 2. 1986 when I gave a mobile CB that I was no longer using to my then boss. After hooking it up and turning it on, I initially thought it was broken because there was absolutely no noise and no signal level. A combination of low sunspot activity, a dramatic decrease in users from the '70s peak, and no interference from computers and/or wireless transceivers (there were none) made for what had to be the golden age of quiet CB. 3. 2017. I think I'll refer to this as the interference age. From the moment I first hooked up the old D201 to a dipole here in the house I was immediately confronted with "noise" and this was different from the CB traffic related noise I heard 40 years ago. This was interference that had to be mitigated with a combination of deployment of the noise blanker and full throttle on the ANL. These were two features I never even used 40 years ago because I couldn't see that they made any difference whatsoever back then. When I later put the old Browning LTD in the truck and drove around town with the unit on, I heard very little in the way of actual CB chatter. I did hear the same type of interference noise except that in this case, the interference increased at every intersection. The overall baseline signal level is certainly lower than it was in the seventies, but nowhere near as quiet as I heard there in Richmond in 1986. My gut tells me this interference is due to the proliferation of CPUs and wireless transceivers even though both the CPUs and the transceivers operate at much higher frequencies.
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Post by capn357 on Feb 17, 2017 22:41:18 GMT -5
Nice, thanks! I tested the sound out today (not para-metrically, just what it sounded like through another relic of mine (Browning LTD)), and it sounded plenty loud to me as I drove around town while my assistant yapped on the tram. I'm anxious to actually measure the modulation %, but I don't have the equipment to do so at the moment. I'll likely wait to dive into the carrier power adjustment until I'm able to see the results of that measurement.
Now my challenge is that I don't think my property is very "CB base station friendly". I'm kind of in a hole so I don't think I'll be able to achieve much range here locally. Then again, it was always talking skip that interested me as a kid and I suppose I should be able to manage that reasonably well, even from the hole (assuming I put up a decent beam antenna, which I'm sure the snooty neighbors here will love).
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Post by capn357 on Feb 17, 2017 11:28:44 GMT -5
Alright, so let's presume my rig is undermodulated. Suppose I wanted to back down the carrier power to a level where my Audio section (however modified) can more adequately modulate the carrier. Can that be done without a wholesale change of components or without completely detuning the RF final section? (I'd like to just add a volume pot to the input of V700:D).
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Post by capn357 on Feb 16, 2017 20:56:42 GMT -5
An average reading wattmeter like a Bird 43 is a great indicator of modulation unbalance. If you have more positive peak modulation, than negative trough modulation, the meter will swing forward when you talk. The converse is also true. And it looks like you are seeing a backward swing when you talk, which means your negative modulation is stronger than your positive. A good rule of thumb is to observe what the power reading drops to when you fully modulate, and that level should be where you set the dead carrier power in order to not back swing when modulating. A 25 watt carrier will need to swing to 100 watts PEP to make 100% positive modulation. The 6L6 audio tube should have enough power to support that. But the rest of the circuitry may not be completely up to snuff considering it was only designed to deliver maybe 20 watts of peak modulation. The other factor may be the 6146 itself. Usually, in ham rigs, it takes a pair of those tubes to put out 100-120 watts give or take. So a single 6146 may not be able to deliver 100 peak watts. You got me to wondering if indeed something else was modified along with the RF final section when the 6146 was dropped in so I took the bottom off of my unit and the newly acquired "standard" unit and compared the two. It certainly appears that my audio board has some extra components added to it, at least compared to this other unit. I put a high-res photo of my audio board in my box account at: app.box.com/s/j4cus5rc1cumm2160vqafow08ouoryo4 If you guys are curious at all and have the time to take a look at that photo, I figure you can easily tell if this looks standard or not. I will say this, from a heat damage point of view, my unit sure looks a lot better than this one I picked up recently. The only sign of any heat related damage on my juiced up unit is about a half-dollar sized discoloration in the upper corner of the BA board; everything else looks great. On the other hand, this standard unit that I just bought shows a fair amount of heat damage on the receiver board and the BA board is completely discolored. Maybe the previous owner let his cat sleep on top of the unit while he was talking on it.
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Post by capn357 on Feb 16, 2017 0:31:38 GMT -5
Using the manual side on SSB is a waste of time. We did a lot of this and that trying to stabilize the VFO. A zener diode to regulate the B+ to the VFO has no effect on this. Tried it. Finally found what causes it. When you key the mike, the transmit circuits draw more current from the power transformer. This causes the filament voltage to fall, just slightly. The only tube that is affected by this is the VFO side of V302. The tiny drop in heater temperature in the tube is what causes it to shift frequency on SSB. When you unkey, it slides right back to the frequency it gave you on receive before keying the mike. A fanatic could probably regulate the heater power to V302 and fix this. Never had a customer fanatical enough to ask how much it would cost, let alone offer to pay for having it done. But that's what we discovered. Bear in mind that there is more than one way to wire up the "Xtl-Man" switch for using the VFO to transmit. Some hookups cause the frequency to jump when you transmit. Nobody notices on AM. The simplest hookups will cause this frequency shift and the AM operators won't notice or care. The hookup we worked out is more complex, but still won't fix the heater-voltage problem. Oh, and that 6146 mod for the final was circulated on the 'net ten or fifteen years back. Best I can remember it was a guy named Gary Bedell in California who worked that out. He has been gone for nearly ten years, IIRC. Maybe. Been a while. To run a bigger final you need more audio wattage to modulate it. Gotta figure that the audio level would be reduced with this setup unless you also make the modulator section bigger as well. 73 That is extremely interesting (about the heater power)! Thanks so much for taking the time to share that. Regarding that 6146 mod, mine was performed by a fellow in Fairfax (or possibly Falls Church), Va in '76 or so. I can vaguely remember riding to the guy's house with my father to pick up the unit. What I can't recall is if I ever operated the D201 unmodified or if we had it shipped directly to this guy for modification at the time of purchase. Regarding your and Sandbagger's comments that the AM modulation must be reduced, I suspect that is indeed the case. Whereas a recently purchased unmodified D201 will dead key at 4 watts and swing a bit higher when speaking into the mike (as shown on a bird 43) my 6146 based unit dead keys around 25 watts, but then shows a decrease in power (again on the Bird 43) when speaking into the mike. I wish I still had my buddy's Agilent Fieldfox so that I could see exactly what's going on with the carrier and sidebands, but I just sent that back to him about a week ago. If only I had stayed at HP a while longer in the 80's AND if only I had not then lost complete interest in CB's in general at that time, I could have acquired an entire HP bigfoot test system (8903 audio analyzer, 8656 sig gen, 8902 measurement receiver) for nothing! The guy that took my place now has that setup in his house in Richmond.
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Post by capn357 on Feb 14, 2017 1:17:27 GMT -5
We never did run an amp in combination with this unit, but we did have a Wilson 12 element laser on the roof. What a monstrosity that was! I remember being amazed that my mother let us put that thing up. It made the little ranch house we lived in look like the fuselage of a helicopter. I think my mother still has an old photo that I'll have to try to find the next time I'm up there. We lived west of D.C. and I was able to talk all over the U.S. although I recall most of the contacts were east of the Mississippi. There was a boatload of noise on every channel (all 23 of them:D) back in those days. I still have a stack of the postcards I received from the folks I spoke to; I can't believe all the trouble we went to back then just to "prove" we talked skip somewhere.
Anyway, regarding your comments about the modulation, I don't know whether this mod to the RF final included any modification to the modulation section or not. I do know that the system sounded great with the standard non-amplified D104 back then. I'm not sure it has the same punch today although I don't (yet) have a decent antenna to do it justice.
Your comments about the compromised reliability are duly noted. I doubt we would have had this modification performed if either my father or I had really understood what was involved. Then again, here I am 41 years after the fact and the rig still works, although I'm sure it is on borrowed time. I had an Agilent Fieldfox analyzer that belonged to a former business partner of mine on hand that allowed me to align the synthesizer. There were some banks of channels that were way out of whack and the USB was all over the place. I was able to bring all but one of the crystals into alignment so channels 5-9 are still just a bit off on AM and LSB, but I can bring 'em back with the clarifier set to 9 o'clock.
Speaking of all of this, I recall one particular annoying "feature" of this radio back in the day that I want to run by you for comment. I did a lot of talking on sideband back then and I was always under the impression that this unit transmitted on a slightly different frequency than it received on in SSB mode. The reason I say that is because when I would tune someone in so that they sounded right, that person would always need to retune to get me to sound right. I eventually just got in the habit of letting whoever I spoke to do the tuning and then I just lived with him or her sounding like a chipmunk. Ever heard of this happening with other D201s?
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Post by capn357 on Feb 13, 2017 14:13:59 GMT -5
Anyone familiar with a modification for the Tram D201 that replaced the normal tube in the output section with a 6146B-8298A tube? Way back when in 1976, my father sent our Tram D201 to a guy to have it modified so that it would transmit on the "manual" tuning selection. At the same time, I remember the guy saying that he bumped up the power, but I didn't know the details. 40+ years later, I fired it up and compared the inside of mine to pictures of units being sold on Ebay. It was only then that I noticed the extra cord connected to the top of the rear most tube in my Tram's chassis (see photo). After examining that tube, I saw that it was a 6146B-8298A. The unit dead keys about 25 watts on AM according to my bird wattmeter. Attachments:
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Post by capn357 on Feb 13, 2017 14:06:52 GMT -5
Thanks.
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Post by capn357 on Feb 13, 2017 7:04:13 GMT -5
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. Attachments:
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