Dedicated to the Collins 30J transmitter



David Eppert(VE7CN / VE7EPP) Restoration

I received my amataur radio license in December 2008. About a year later, I visited a local ham's QTH and expressed my interest in having a tube radio to complement my modern station with the hope of contrasting the two eras. He described some of the radios that he may sell, one of which was the 30J and told me he would let me know if and when he decided to actually sell it.

Well, over our frequently scheduled dinner meeting in 2012 which includes another local ham, he mentioned that he is selling it and had advertised it for sale. I told him right there on the spot that I had to have it. I went home and at 11pm I told the XYL that I was going to go get it. She told me that it was too late. I called and it wasn't too late so I went and picked up what parts I could move by myself. I was excited but the excitement just grew from there. I knew that I had acquired the statement that I was hoping for but even better, as I learned, it was backed by Collins quality and history. WOW! Not only was this my first tube radio, it was my introduction to Collins. I'm hooked.

The restoration of my Collins 30J-18 is nearing completion. With so few 30J's left in existence and considering there were production variations, it is difficult to identify if various parts are original. Of the 30J's that do exist, some have been restored with what parts are available thus leaving the question open; What is original supposed to be? I now have all of the parts and will continue to post pictures and updates in an effort to present as much detailed information as possible since I believe that my 30J is extremely close to original. It is very encouraging to read J.B.'s message that my 30J is the nicest condition that he has seen.(pre restoration I think)


I intend to try to keep all of the original parts in place so I simply clipped the leeds to the original caps 11 - 17 and added new caps. Caps 12 and 13 are in series so the two 600V 4mfd caps were replaced with one 600V 10mfd cap.

I could never make a modification to a radio like this but someone did. From what I can see, there has been two modifications.

The first modification was the installation of coax and connectors for an unbalanced configuration.

Two sets of holes were drilled in the top of the chasis, one in the center and one towards the rear, for surface mount coax connectors. I fitted an antenna relay switch into the center hole and it fit perfectly between the two coax cables run from the meter panel and to the connector mounted into the second hole at the rear. The 110VAC wires lined up with the terminals on the relay. The antenna relay has auxiliary contacts which will be used to automatically switch the receiver into STANDBY when the transmiter is switched to SEND. I haven't yet connected the 110VAC power wires.

The second modification was to the RF Unit as seen in the picture below. A combination provisioning for a VFO and possibly replacement of the 5 pin crystal socket with a 3 pin crystal socket. The current 3 pin crystal socket looks like a perfect fit so it may possibly be original however the manual describes a five pin crystal socket and references the Collins Type 2C and Type 294 Crystals.

When I received the transmitter, it was missing the original Plate Transformer. With the help of JB and a Ham at Hammond MFG., I purchased a Hammond Model 733 2,500V C.T. Plate Transformer. Since there is no need for the dual primary, I decided against the Hammond Model 733A. I later received a very clear photo of an original plate transformer from another fellow with a very troubled 30J. I emailed the photo to the fellow I got the radio from and asked if he could forward it to the fellow he got the transmitter from who recalled seeing the transformer and found it stowed away under his stairs. As you could guess; I was extatic. Here it is.

Just what's inside those 131C-11 Grid Coils? I took a few pics. The schematic is in the manual. I believe this open coil below has been modified (windings shortened) for 40 meters but the Collins tag on the one that I opened (not the Collins tag in the picture below) shows 4200-5700KC.
Here are a few Collins 131C-11 Measurements.

March 5, 2013 goes down in history as the most excitement I've ever had in ham radio.

I spent a few hours today checking connections, tightening screws, connecting the antenna relay with accessory cable to the receiver, and double checking coil pinouts.

We powered up the filaments on the 30J expecting the worst just to avoid disappointment. We used a variac and brought up the power slowly. The first sign of light/life was the front Filament indicator light getting brighter and brighter which caused excitement because it lit up and there was no smoke. Slowly the tubes started to glow. On the power unit we watched for the glow on the 45 keying rectifier, the two HV 866A rectifiers, the two LV 866A rectifiers, and the 5Z3 Bias Rectifier. Not all of the 866A's appeared to be glowing. Regardless, the huge smile on my face was hard to miss.

The two 6F6G's on the Modulator unit also started to glow. We left the ZB-120/C-120 modulator tubes out since they are so rare. Next time I'll have them in. The aluminum shields around the two 6J7G's ensured we couldn't see those tubes.

Now for the RF Unit. The two 813's had the brightest glow second to the 802 and the three 807's.

Our first test went exceptionally well. We brought the power down using the variac. The first test was complete but we didn't quit there. We replaced all four 866A's with four 3B28's and brought the beast alive again using the variac. All went well with our second test. We let it sit for about a half hour while I learned to operate split from an expert. This made the day even more exceptional, operating cw split next to a glowing warm 1930's tube transmitter. Wow.

The 30J is resting now. I'm looking forward for the next test, the HV test.

The Output Netowrk Replication

Well, someone had the need to replace his missing output network on his 30J so I took mine apart and had an aluminum cast copy made.

I had some spare parts so I have been making a complete copy. Here is where it is at now. April 20, 2013.

The aluminum strips were cut from sheets and cut to size and drilled to make up all of the aluminum connections. There was quite a bit of grinding, drilling, and sanding. I found the capacitors on ebay and dug out a bunch of banana plugs and sockets.

The picture above is a replica of my output network that I made for another 30J owner. I really enjoyed making this.

And now that my output network is reassembled and installed back into my 30J I can now continue my power testing and get it on the air. April 20, 2013.

Well, I now have a Collins 310B VFO for use with my 30J. I've just finished recapping and reversing mods and am almost ready to test it out. July 23, 2013.

A picture of my 30J now.

August 28, 2013 was a good 30J day. We warmed up the tubes for 30 minutes but had the ZB120 modulator tubes and the 813 finals removed and then followed the tune up instructions in the manual. With the Telephone/Telegraph switch set to Telegraph and the filament switch on and a key connected to pin 1 and 2 on the H unit(bottom leed connector panel), we switched the Send/Receive switch to Send and keyed up and heard the tone at the crystal frequency on the receiver nearby. We adjusted the A,B,C,D,E dials on the RF deck as instructed and did see some movement on the plate meter but not the dips we were hoping for. The same with the Grid current. It's been a while since we last powered it up so after refamiliarizing with the radio we powered it down and will go at it again tomorrow.

OK, September 27, 2013 we got 230 Watts out on CW. It was a challenge tuning the RF deck and output network but we did it. We grid dipped the exciter, grid, and output network coils and all seemed to read ok for 80 meters but the exciter coils and grid coil were wrong. Taking another look at my 80 meter coil and comparing it to a picture of one sent to me by Gary, it appeared the same to my novice eyes but Gary's was double wound. The Grid coil reads 3000-4200KC which one would think was correct, but not so.

So, what we did was use a spectrum analyzer to see what was happenning. With an 80 meter crystal in the socket, we saw a higher peak on 7MHz than the one on 80 meters as well as small peaks at multiple harmonics. We then chose to take the crystal frequency with the capacitance of the first amplifier tuning condensor, (since the tuned circuit at the oscillator is bypassed on 80 meters) and cross referenced it with a tuned circuit calculator, only to find that the exciter coil we were using was the wrong inductance. We constructed a new one and bam. Then the same for the second amplifier grid tuning condensor. This is where the grid coil labeled 3000-4200KC was also giving us a strong peak on the second harmonic. This is more difficult to construct so tried another grid coil. We tried one labelled 2100-3000KC and again it worked. Then we tuned up the output network until we read maximum output on our output meter; 230 Watts key down. That did the trick. There are actually five tuned circuits in the RF deck and output network of this transmitter and we made it through all of them.

We tuned the transmitter up again and plugged it into an antenna through an antenna tuner and read 230 watts out on CW. What a great day in my life.

There are a few items on the list now to figure out. The first is that even though we are getting 230 watts out of a 250 watt transmitter, we are seeing about 10ma less grid current than the manual states we should be seeing. The other item is that there is a bit of a hum on the output and some RF going out with the key up. We'll give it a couple of days to think things through and then we'll most likely check all of the voltages throughout the transmitter referencing the "Voltages occuring in the 30J" page of the manual.

Here is a picture of the remote box I made. It is 10"x5". I found a 6" Collins winged emblem on Ebay to match the one on the 30J. The PTT switch on this remote box will allow me to put the transmitter into transmit mode rather than using the SEND switch on the front of the 30J. . The manual shows the connections. I am using 110VAC relays with 6VAC going to the remote box which indicates filament and plate power ON/OFF with the matching red and green lights. The relays are at the base of the 30J so I don't have 110VAC coming back to the remote box as.

We had the output network configured for a balanced output with a 4:1 balun at the output. This configuration got us 230 watts out on CW but the grid current is 10ma lower than it should be. Since we now know that the RF deck is tuned properly for the crystal frequency and that the output network wasn't the problem with getting RF out, I'd like to try an unbalanced configuration. I have therefore removed the balun and the connections to the original ceramic insulated antenna terminals(one capacitor to antenna terminal 1 and the second to the RF meter to antenna terminal 2), and installed the phasing coil. I've installed an antenna relay in the holes that were made by a previous owner which fit the relay perfectly so there are two external antenna connections on the top of the transmitter, one for the unbalanced antenna and one for the receiver. The antenna relay has accessory connectors and I have wired it to put the receiver into standby when the send switch is activated. Here is a picture.

January 3, 2014.
Well, one full year has gone by since I wanted to get on the Heavy Metal Rally with the 30J. I missed this last one as well. Next year I guess.

I reverted back to balanced output setup on the output network with a 4:1 balun at the output connection since my unbalanced setup attempt didn't yield any good results. I'll try it again another time.

The modulator tubes were kept out of the transmitter until we were comfortable with the voltages and currents since the tubes are so rare. As it turns out, after we got so far, it was suggested that we put the modulator tubes in and the grid current would go up and screen voltage would come down. Well that did the trick. Not only that, during a previous test, we used the Collins 131C-11 grid coil for 2000-3000MC and that allowed us to get 230 watts out previously reported but the coil for 3000-4200MC wouldn't. Since adding the modulators into the picture the radio now puts out 325 watts using the 3000-4200MC coil on 3.885MHz CW, obviously into a dummy load and briefly into an antenna when the band was quiet.

Well, the problem I am trying to address is the varying voltage in my shack. The 30J likes 110VAC however my home service constantly changes so when I am warming up the 30J with the variac set at 110VAC, I watch the voltage on a watts up meter drift from 107 - 113VAC. I have a commercial regulated power supply taken from service at a commercial transmitter site that puts out a constant 118VAC and a variac from the same site that has adjustable input and output. I'll wire that up this week so I can feed a reliable current into the vintage radios. After that is setup, I'll go on to tuning the 30J again, letting the modulator tubes warm up another 18 hours for a total of 24, and then test AM operation.

January 9, 2014

Well, my very first Collins 30J-18 CW QSO was just made with VE7XF using my call VE7GV.

I was using a Collins 310B VFO and a Collins 75A-3 Receiver along with a straight key. The 30J put out 325 watts and we both reported +60 signals. Time to sleep. Here is a picture of my vintage shack taken just after the QSO. I didn't leave it in TX mode, just turned it on briefly so the red light would be on for the picture but didn't have the key down.

January 22, 2014

Well, a few days ago I tried tuning the output network coils to try to bring the plate current down from 400ma to the 300ma in 80 meters that the manual specifies. I ended up with a bunch 40 meter RF in the shack and the led lights below the dummy load lit up.

The following day I turned on the 30J and the pair of 807 buffer tube filaments didn't glow. Dang it. Well, I went through with a volt meter starting at the tube socket and working my way down to the modulator deck where the traces ran and shared the 6.3v with the filaments of the 6F6's and 6J7's, and then to the power supply deck where the filament transformer was. Of course, there was no voltage on the filament pins.

I remembered reading Gary Halverson's restoration story and he mentioned a similar problem but with different tubes where the transformer taps are rivetted to the screw mounts for the filament leeds. I measured resistance to find opens or shorts and yes, inconsistent readings at one of the rivet points on the 6.3v tap on the transformer. I flowed solder on the intermittent connection and the readings were better. Well, it took quite a while to put it all back together so I'll have to reinstall the power supply in the chassis tomorrow and see if that did the trick.

Here is a picture of the transformer leeds with eye hole connectors rivetted to a phenolic board. The underside screwed in leeds that go to the filaments. This picture was taken before I flowed solder at the eye hole connect and rivet

January 27, 2014

We just made the first AM QSO using the 30J. I used the 30J with a Collins 310B VFO and a Collins 75A-3 Receiver. What an awsome experience restoring this beautiful transmitter. I am very excited. The first CW and AM QSO's are logged with VE7XF who gets credit for all of his help and all of the time spent teaching me not only what I needed to restore the 30J but so much more. Thanks XF.




LAST REVISED January 23, 2014