Live To Air – National NC-101X finally back together tonight newly installed coil rack, with the bronze bushings and fabricated band indicator. Slides like it’s on glass, super smooth and low effort.
Listening to the melodious tones of the old Gray Hair Net, using Amplitude Modulation, on 160 meters shortwave. Exact frequency is 1.945 MHz. Not bad for a 80 year old radio, I think the original owner W1KEK would be pleased to know that his treasured set, that he bought back in 1937, has returned to the air.
Very pleased with how this project turned out. The audio is very sweet, with some nice wide bandwidth for hifi AM audio. Just waiting for the electrolytic filter capacitors to finish the project.
Of all the T-368 transmitters known to have been manufactured, and yes there are ways to track these things, only a few are known to still exist.
Email me to add yours to the list!
Total manufactured: 2251
Total known units: 103
I remember visiting Fair Radio in Ohio in the lat 1990s, and seeing stacks and stacks of these sitting inside warehouses, outside rusting away, in various states of repair.
Uses a single UX-210 tube, built by Al Wentworth – Lexington, MA K1BSX (SK April 2004), based on a 1928 QST article.
Click here for the August 1928 QST article “Overhauling the Transmitter for 1929 – Ross Hull” in Abode PDF format.
Collins 30K-1 Transmitter Restoration
The Cleaning, Restoration and Service of a Collins Time Capsule
Shipping a 400 lb transmitter across the country is no easy task, but thanks to a
good packer and BAX Airfreight it arrived safe and sound in just two days!
You can’t use Styrofoam peanuts with these heavyweights, nothing less than high
density packing foam will do the trick!
The 30K-1 RF Deck, with a W7MGA mod, the DPDT knife switch attached to the
bandswitch. MGA was using multiple antennas and his implementation of a
switching network was both elegant and easily reversible. For my purposes, a
single antenna fed with balance line, I removed the switch. Thankfully he had
left the bandswitch connectors hanging on a loop of wire on the inside of the
cabinet, it was simple to reinstall for a single output.
The one and only casualty of the cross country move were the four porcelain
standoff insulators which attach the Output Network to the front cabinet. It
would appear that the inertia of the moving was too great. Thankfully my
junk box yielded four perfect spares!
The back of the meter panel and top of the RF Deck, prior to cleaning work.
The removed Output Network, prior to cleaning. Note plug in coil set on the left
side of the air variable cap, I have both the low and high band sets, so the TX
will cover 75 – 10 meters.
The Output Network after cleaning, a quick trip through the dishwasher did
the trick, washing away nearly half a century’s worth of dirt and dust.
The Front of the RF Output Network, note the insulation panels on the front of
of the unit. I assume these prevent arc over from the meter terminals.
The cleaning of the RF Deck. The large Johnson cap was removed and
disassembled for a through cleaning. Sure it takes time, but look at the results!
The Modulation Deck before and after cleaning photos. Love that 75th glow!
I did have a problem with the audio gain pot on the audio deck, the
unit was defective and a replacement 500K A/B pot was found and installed.
Low Voltage Deck
The Low Voltage Power Supply Deck, before and after cleaning. The unit
cleaned up very nicely, no repairs were needed, other than cleaning relay
HV Power Supply Deck
The High Voltage Deck, shown with the 866 rectifiers removed for cleaning.
The 30K-1 cabinet with all deck removed and ready for cleaning.
30K-1 Tour After Cleaning
Amateur Radio Station W1UJR
*Circa August 13, 2005
Today in the middle of a FB QSO with K1MVP the plate blocking capacitor in my 32V crapped out.
This was evidenced by an immediate loss of RF, a loud hum and the telltale pegged plate current meter. Even my trusty old buzzard RF indictor, a large neon bulb JS lashed onto to my balanced feedline terminals, showed no glowage, a very bad sign. When something like this happens out of the blue, a thousand thoughts run through your mind. Is it the final tube, did I inadvertently hit some knob, did the modulator transformer give up the ghost? I quickly unkeyed the transmitter thinking my antenna relay had stuck, as Dowkeys sometimes do. A check of the relay showed that all was intact and the fault must lie elsewhere. Switching between bands or from Fone to CW had no effect, still a pegged plate meter. I considered that something may have happened to my antenna or feedline, but transmitting into the dummy load brought the same result.
I should mention that this was my Elmer’s, W2UJR – now a Silent Key, former transmitter, so the thought of some major failure made my heart sink. When I obtained the unit from Dick’s estate, I had brought it back to life by replacing a stubborn failed screen bypass capacitor on the 4D32 final tube. Since that time it had run flawlessly, despite the somewhat troublesome reputation of the 32V series. The unit had followed me from Buffalo when I moved to Maine and had become my backup 75 meter transmitter at the office. Rumor had it that Dick only ran it on CW as he did not care for the lack of civility on 75 meter Fone.
Ironically I had just been on the telephone earlier in the day speaking to my friend and fellow Collins enthusiast, Bill K2LNU. Bill shared that, after he had spent countless hours working on them, he was now seriously considering selling some of his Collins 32V transmitters because they were such a project to service. With that cheery thought in mind it was out of the cabinet with the 110 lb transmitter, an exercise which had become an all too common event.
I say common as for most of the proceeding week I had been working on a new acquisition to the W1UJR hamshack. A exceptionally recalcitrant Collins 32V3 which displayed a most troubling linearity fault with the Permeability Tuned Oscillator (PTO). It was only after multiple attempts to diligently adjust the linearity, as specified in the service manual, each involving a trip in and then out of the cabinet, that I discovered that the linearity simply could not be restored to the 50 year old PTO. A returned call from Collins guru Howard Mills W3HM confirmed this and I was informed that some years back Dallas Langford had discovered that the ferrite compound used by Collins in the PTO changed its molecular structure with time. So it seems that unlike wine, ferrite does not improve with age, hence the PTO would no longer track properly. As the PTO was a relatively recent invention at the time, Collins had no way of knowing of this during the initial design of the 32V series. Indeed its doubtful they anticipated their handiwork would still be in used half a century later, so no provision was included in the PTO design to compensate for the ferrite change. Anyway, back to our story.
With my failed 32V on the bench I did a quick check of the mica capacitors used in the output loading network. In the 32V series these capacitors are always suspect and have a high failure rate, especially when used with non-resonant antennas. Still, each of the mica loading capacitors checked fine with the DVM, not a fault among them. This meant that I had to dig digger, or in other words this going to take some time. The next step was to remove the plate connector from the top of 4D32 final tube and see what happened with the plate current. I suspected that the tube had perhaps experienced some catastrophic internal failure. Yet again I was stymied, the tube tested out fine, and I still found pegged plate current with the tube plate capacitor removed.
Curiosity got the better of me and I then removed the tube completely from the socket and applied plate current, same result, pegged plate meter. Since the final tube was entirely out of circuit and I still had excessive plate current, as a quick test I removed the coax connector from the rear of the transmitter, Eureka, plate current was now at zero. I now knew that a fault existed in the output network, but where? The 32V series is one of the most tightly packed and difficult transmitters which I have worked on. Despite Collins excellent manuals and documentation, service on these units requires both a great deal of patience and dexterity.
At that very moment I was on the air with Larry NE1S, yes, multitasking. Carrying out a QSO and checking for plate voltage may not be the wisest course if one wants to enjoy a long life. However, in this case it had a payoff. I described the fault to him and explained my findings. Larry confidently asserted that, given my symptoms, it could only be one thing, a failed plate blocking capacitor. With the transmitter keyed, I checked for plate voltage at the RF connector, 890 volts! Sure enough, the plate blocking capacitor was allowing full plate voltage to show up on the output of the antenna! Instead of blocking the plate DC, it was in fact conducting it! Not exactly a safe thing, in fact it was downright dangerous. If I had not had the tuner in line, full plate voltage would be applied to the antenna feedline and leads, ready to zap some unsuspecting passerby. So with that discovery, the next logical step was to unsolder one lead of the plate blocking capacitor. A resistance check showed that my plate blocking capacitor was now a resistor, reading about 23 ohms on the trusty Fluke meter.
The capacitor in question is one of the older square mica capacitors that you see in transmitter output networks, with two mounting holes and solder tabs on the end. This capacitor in particular was rated at 2500 working volts and 5000 test with a value of .001. It displayed no visual sign of failure, no burn marks, case swelling or discoloration. For all intents it looked like a good capacitor, in fact it looked new.
As I mentioned before, the 32Vs are a real challenge to service.
If you have ever had the joy of replacing the plate blocking capacitor in a 32V, heck if you have done any service at all on these 32V series rigs at all, you know what a project this was. A quick check of the spare parts bin yielded the needed capacitor, those $5 coffee cans of parts dug out from under tables at hamfests sure do pay off.
However, finding the capacitor was the simple part. It took me nearly 90 minutes to remove two screws and solder connections on the failed capacitor and install the replacement. The Collins design team had conveniently located the plate blocking capacitor about 3/8 of an inch from a large wound loading coil. Since access to the Phillips head screws which retained the plate capacitor was simply not possible with a screwdriver, I had to settle for turning each screw 1/8 of a turn at a time with a pair of needle nose pliers. So to say things are tight inside the 32V is a major understatement.
Curiosity and abundant spare time got the better of me and I decided to open the defective capacitor up for an examination. After all, things that zorch out are often pretty interesting to look at. By examining the exterior of the capacitor I could see a manufacturing molding line around the upper edge of the case.
Using a bench grinder, I carefully ground away the edges of the case, removing the bonding joint of the upper and lower sections. A small chisel was then used to split the case halves open for a visual inspection. It was quickly apparent what had failed on the capacitor. The center section of the mica had been carbonized from end to end, essentially creating a carbon composition resistor. No wonder at all that I measured 23 ohms of resistance across what was once a capacitor.
So, can those more knowledgeable than I, which is probably a good number of you out there, offer up an explanation why this occurred? Operating plate current was normal, perhaps a tad conservative before the failure as this is my Elmer�s former TX and I run her lightly.
Did the 50 years finally catch up with the capacitor, or did the Zorch Gods just decide it was time? Are there other causes for this? If so I’d like correct them so I don’t have to replace another.
This is the rig which formally belonged to Bill Orr W6SAI, the well known author and a former editor of the “West Coast Radio Handbook”.
Born May 27, 1924, John enjoyed a very full life, as member of the US Army during the occupation of Japan, as a petroleum geologist, traveling throughout the work, as a private pilot who had owned several plans over his lifetime – holding an instrument rating, a most skilled gunsmith and nationally ranked pistol champion, and finally as a ham, with a life long interest and love of radio. It is in the radio context that many of us many have encountered John, and his creations. He was both well known and very well regarded with the vintage radio community, perhaps best remembered for his wonderful home-brew rigs, often built on cherry wood.
He was also an amazingly generous man, happy to answer any technical question, and frequently giving out gear to others, with the only request that they use it on the air. I was recipient of John’s kindness, with the gift of the W2ER rig, a transmitter that John built some years back for Marshall W2ER SK.
I had the privilege of finishing up the Linc Cundell Contest report for John during his illness. While reviewing the logs, it became quite clear how well regarded he was, almost every log entry included a personal letter or card wishing John the best, and thanking him for
73 Bruce W1UJR
This was written by Tim, W1GIG. (Thanks Tim!):
John passed away on March 18, 2008. It was 11 years ago that Bruce Kelly asked John to take over the Amateur Radio column in the OTB as Bruce himself was winding down. John was a man of many talents and had a most interesting life. Because he was always so busy helping others, he rarely took time to talk about himself, so I am going to take this opportunity to tell you a bit more about him.
John was born in Guatemala of American parents where his father worked for United Fruit Company (think bananas). At an early age, his father died of malaria and his mother moved the family back to New England. He also lived with an Aunt and later with his much older brother, an airline pilot, who lived on Long Island. As a teenager John discovered radio and his brother bought him a $5.00 two tube regenerative radio kit to build. John built the kit, but it was another 6 months before he got another kit for the power supply. With the help of a ham who lived nearby, he got the radio working which opened up a whole new world for him. John was in High School when his brother went with him into NYC to test for a ham license at the FCC Field Office. For the next couple of years he was active on 40 M. CW using the regen receiver and a Hartley oscillator.
At this point, WW II got in the way. John enlisted in the Army and was trained in radio repair, shipped off to New Guinea, and assigned to be a telephone lineman. The Army moved John steadily North to the Philippines and then to Japan where he was finally sent back to the States for discharge. John enrolled at the University of New Hampshire where he discovered his love of geology. He liked it so much he went on to get a Masters at the University of Nebraska and several years later, a Doctorate also from the University of Nebraska. He continued to work for Chevron exploring for oil in Africa, Madagascar, Spain, Denmark and many other countries including the US.
While he was in college, John remembered his love of radio, but unfortunately his ham license had expired, so he went back in 1954 to test again receiving the call W1FPZ which he held ever since. Later, he tested for his ham license in Madagascar (in French) and in Uruguay (in Spanish). Not many of us have tested for our licenses in three languages! While he was in Madagascar he built many of the transmitters that are still in use at his home. He even wound his own power and filament transformers to get the voltages he wanted.
John also discovered that he was an excellent pistol marksman, but that his results could be substantially improved by reworking the guns themselves, so he taught himself to be a gunsmith. His skills at woodworking, carving, machining, precision casting of bullets and loading target shells were such that this became a major hobby business for him which he pursued right up to recent months.
John was a survivor. While in the Army he survived a major brush with a 3,300 volt power line and later a plane crash while in Africa. Since small planes were the only way for John to get to his job sites, he decided that he’d rather trust his own skills as a pilot than relyon the brush pilots that the oil company had hired. Back in the States, recuperating from his injuries, he got a private pilot’s license, then went on to a multi-engine commercial license with full instrument ratings. Just before he retired, he was working out of Denver and flying his own twin engine Queen Air to Maine to work on his retirement home. He even flew from Maine to the AWA conference one year picking up MarshallEtter, W2ER from Long Island on the way.
Preparing for retirement, John and his wife Liz doubled the size of their new home in Maine. As part of the project, John wanted reliable ham communications with his friends around the world. Limited by normal power regulations, he decided to build a BIG antenna. His final choice was a horizontal V beam aimed at the Southeast. The beam legs were 1,100 feet long and supported on three 100 foot towers. Looking for wire strong enough to span the distance he ran across an ad for #6 phosphor bronze wire run by Marshall, W2ER who had salvaged the wire when he was closing the RCA site at Rocky Point. The two men became fast friends and co-conspirators. Marshall provided quality parts left over from RCA and John, using his metal and woodworking skills, customized the parts to suit his projects. The result was a long series of radio projects that he gave to friends with the caveat that they were required to use them on the air in AWA events.
John always had a fascination with the products of Jerry Gross of NYC. He built a Gross replica transmitter for Marshall who used it for many years. Parker Heinemann, W1YG found an original Gross and had John restore it along with the receiver, station monitor and antenna tuner. They set up an entry in the 1991 AWA contest that exactly duplicated a Gross add from the 30’s and took first place. After the conference, John got a call from Bill Orr who offered John his Gross if John would restore it. That transmitter is part of John’s home station.
Not satisfied with the Hartley oscillator, John discovered that if he used the Colpitts circuit with a split stator condenser and grounded rotor, he could eliminate the hand capacity effect. One of his last projects was to set up the tuned circuit for me and share several of his other construction secrets. The circuit is rock stable on 40 meters.
Thanks for the opportunity to fill you in on some of the less well known aspects of John’s life. It was an honor to know him and he will be missed by all.
Two Stage Telegraph and Telephone Transmitter built by AB9ZG.
One of my antique radio friends built this transmitter some years back, a very true and authentic reproduction. I admired it at the time, not sure I ever worked him with it, but remembered it fondly.
Jon, the builder, kindly entrusted it to me as the caretaker, and looks like, given the weekend weather, I’ve finally got time to get it unpacked, tested, fired up, and on the air. Long, cold winter nights in Maine are ideal for radio.
I was therefore delighted to be contacted a few weeks by Jon, asking if I had interest in his creation. In any case, wanted to share Jon’s handiwork with my radio, and non-radio friends.
It is crystal controlled, you can see the xtal on the right of the upper deck.
The upper desk is the RF section, and the lower deck the power supply and modulator.
Ideally I’d like to find or build an old table so I can set up a replica 1920/30s station, complete with one of the early National SW-3 receivers.
I’ll post more as I get it on the air and operating!
– Bruce W1UJR
From the engineering diagram, it appears that Utah first offered this unit for sale in late 1937. Aimed the new ham, it was a entry level unit, sold for $15.95, and offered CW only operation. The design is quite simple, consisting of only one rectifier tube, and a single 6L6. Despite the simple tube layout, Utah claims coverage from 160 to 10 meters with the appropriate crystal and coil.
Overall, I found my unit quite clean, but upon disassembly on my workbench to replace the missing line cord, I discovered that the some had replaced the power transformer. Further testing revealed that the electrolytic filter capacitor was shorted, most likely the reason the original transformer needed replacement. The original filter cap was encapsulated in wax, inside a cardboard carton, so a suitable replacement will need to be fabricated. I believe that I can melt the wax out with a heat gun, and install a modern electrolytic capacitor, while still retaining the vintage look. Clearly someone had been working on this unit before, little wiring was connected in the power supply, it appeared that someone had started the project, but not finished. I removed all components from the power supply deck, and will rebuild from scratch.
The RF deck was another story, complete, but very much in need of a good cleaning. In addition, the kit builder was not terribly skilled, and most of the soldering needed rework. These kits were sold as an entry level kit, often to newly minted hams, so one would expect that experience in kit building would be lacking. I have no doubt that the unit worked at one time, but had clearly been sidelined with the power supply failure. As pretty as much of this vintage gear is, I like it to be functional, and not just for shelf ornamentation. So restoration needs to be carried out in a manner which is both authentic, and yet allows consistent and reliable operation. Whenever possible I always use new old stock parts, and this kit will be rebuilt in my usual manner.
Following the same strategy of the power supply deck, I disordered and removed all components from the RF deck, inventorying all in Ziploc bags to ease the future rebuild. The resistors, caps and chokes will be checked, but much of the cloth covered vintage wiring is showing its age, and will be replaced.
With the deck components removed, but leaving the air variable caps in place, I then ran both the RF and power supply decks through my dishwasher, placing them on the upper rack to avoid heat damage. This treatment, really does wonders, and no damage occurs if the system is run on low heat. I would however, suggest removal of any component which has a decal or label.