R390A Solid State Conversion Video #1

[@careycraig4360]

EXCELLENT! This video is what makes Ham Radio and Projects like this so Very Interesting. Great Work!

[@johnwest7993]

I have an Arborphone 27 TRF radio I got without tubes. I looked into it, and a set of tubes was over $100, so I've been considering using plug-in transistors on old tube socket bases. I see from your efforts that it is quite a reasonable plan. Thanks.

[@charlessmith833]

Won't work without proper coupling. Poor results likely if directly connected without observing hi to lo impedance coupling.

[@joed2392]

Hi Charles, Great Job !!! I have always called the 390 a "Clock Box" radio, due to all the gears ! After seeing your conversion, I may finally get a 390 now !! I already have a couple SP-600's, Halli's and Drake's on my "Hollow State" bench. At one time in the past, I considered converting one of my Drake TR-4's using the Satori, Sherwood and others, discrete drop in solid state/tubes ..... But they were pretty Expensive way back when !!! TNX & 73's

[@charlessmith833]

I have converted an SP-600-JX1 and it works great. Look for the video

[@larryb728]

A work of art Charles. I like your "Plug In" solutions.

[@erin19030]

I would love to own one of these R-390. Multi-band receivers. I worked for a radio, company that sub-contracted for Collins on an Army contract. In the Army as a radioman I had several R-390’s in my radio room and mobile hut on a duece and a half.

[@ks1u]

Fantastic work, Charles. I've rebuilt about a dozen R-390As and I've always had in my mind to try this. You've provided the impetus for me keeping the next one I get and doing this mod. Thanks for posting this and please add some additional videos.

[@charlessmith833]

I can save you the trouble if you want to buy this one. I'm downsizing. Shoot me an email to the address at the end of the video it you are interested.

[@EC5ABG]

Impresionante ,muy buen trabajo,👍🤩 73.

[@doncarlton4858]

The heaters were not for cold climates. They were used to insure the crystals were at a constant temperature for frequency stability.

[@charlessmith833]

The AGC strong signal overload has been fixed. The Limiter now works as it should. SWEET SUCCESS.

[@twingonauta]

Fantástico ! ✨🍃👌🎩

[@ElPasoTubeAmps]

I am really happy to run across your video. That is an amazing change you have made for your receiver. Very impressive. I would like to ask you a question. I have the older R-390 and love it. I have done the alignment very carefully and picked the best of the best tubes for it and while it does work, it seem to have that problem I have hear people refer to as a global-sensitivity-loss. I have the equipment and experience to measure all these parameters but it is very hard for me to move this beast around and work on it at will. To solve my sensitivity loss, I added an outboard tunable preamp to it and it improved it immensely. Love it... I now use it for my 20 and 40M AM station. But one last things bugs me and that is the Carrier Level meter. It will zero properly but it just doesn't respond to any signal level. I have checked around it a couple of times but it just doesn't seem to want to work although one time maybe a couple of months ago, it almost came alive. Wow... I have no idea why but now it is worthless again. Do you know of anything common that causes the Carrier Level meter to quit working? My receiver is made by Collins if that is worth anything. Any thoughts would be appreciated. 73 WA4QGA My information and email is current in QRZ.

[@charlessmith833]

These things are old and as with old radios things happen. Use a contact cleaner on all the controls and tube sockets to begin. The problem is in the IF circuitry or meter circuit. I don't know how easy it is to access things on that model. The 390A is a bear to work on under the chassis. The 390A is very sensitive both as a tube and solid state receiver. I don't know about the plain 390. Yes, I hate to pick these monsters up from the floor. They are obscenely heavy. A real problem for a 77 year old.

[@charleslauter5035]

Amazing job! Please convert a few more receivers like a Hallicrafters SX-100. CAL

[@charlessmith833]

The SX-100 has already been done. Click my name and you will find more videos for Hallicrafters and Hammarlund as well as others.

[@MikePeace]

This is Brilliant Charles! Are the solid state tube replacement available to purchase?

[@charlessmith833]

W4AX (Mack) can help you with obtaining professional plug-ins. Find him on QRZ. The PC board and socket parts and pins come from China. You must purchase surface mount parts and assemble the modules yourself. Or you can build them from scratch as shown in the videos using non surface mount parts.

[@jerrydaugherty3781]

Good to see a conversion on a high end receiver. Have you given thought on doing conversion on a transceiver?

[@charlessmith833]

I only do receivers. No transceivers.

[@cthoadmin7458]

This is truely fascinating Charles. Have you documented it somewhere? 73 VK4QP

[@charlessmith833]

I have full documentation. Send me an email (at end of video).

[@MikePeace]

Where can I purchase these solid-state tubes for my R-390A?

[@charlessmith833]

You have to make them. Watch the video R392 Solid State Conversion. The radio requires some mods. You cannot just plug them in without doing the mods to accept them. You can use my email if you want to purchase the conversion manual. W4AX additionally can tell you how to order parts to make more professional looking plug-ins. Look him up on QRZ.

[@brianfletcher9774]

Why did you not replace the selenium rectifier with sold state diodes ?

[@charlessmith833]

Watch video #2 to see the new bridge rectifier

[@Homer19521]

With all those changes you left the selenium rectifier? At least it looks like one.

[@charlessmith833]

That's the original rectifier. It works just fine and is not in the way and I didn't have to add any terminal strip for diodes. But you can certainly replace it with modern diodes if you wish. I left as much original stuff in place as I could as long as it doesn't interfere with the conversion.

[@Homer19521]

@@charlessmith833 - OK you have to draw the line somewhere, but I have read so many accounts of how failed SR's can be dangerous when they fail.

[@charlessmith833]

@@Homer19521 This rectifier only has 25v on it. Not very dangerous. It only provides 25vdc to the antenna relay. Not much of a load. I have seen them burn out in 120v circuits if abused. They stink really, really bad. Any kind of shorted diode in a HV or power circuit is bad news. You mention dangers of failed ones but I don't know how it can be any different or any more dangerous than a modern diode. Perhaps you could explain what the dangers you have read about might be.

[@Homer19521]

@@charlessmith833 Selenium rectifiers had a shorter lifespan than desired. During catastrophic failure they produced significant quantities of malodorous and highly toxic fumes that let the repair technician know what the problem was. (ref: Wikipedia & other sources)

[@charlessmith833]

The selenium rectifier has now been replaced with a conventional diode bridge. See video NO. 2

[@simeonstoyanov9662]

What can you do with this thing??I am from the younger generation.You can catch radio signals from different sources….??

[@charlessmith833]

These radios are extremely stable and well built receivers from 500KC to 32Mc. They are immune from vibration. They are useful to amateur radio service. They are crystal controlled for stability and tuning is accomplished with permeably tuned coils. They were used in military service for years. They are tube radios but I have converted mine to 100% solid state for longevity without tubes.

[@elcocodiaz8297]

I have 1 like that

[@bill-2018]

But why? It's lost all it's valve character.

[@charlessmith833]

Yes Bill, you are right. You lose a lot of nostalgia when you convert the radio to solid state such as burned out filaments, noisy tubes, gassy tubes, weak tubes, burnt resistors, shorted capacitors, bad electrolytics in the power supply, too much heat, high voltage that can kill you and hours of troubleshooting and looking for obsolete tubes. The transistorized version has none of those problems but they are dearly missed. Nostalgia wins again.

[@warplanner8852]

Aside from his explanation above, it's _HIS_ radio.

[@erin19030]

What a desecration of a beautiful rig. You rendered it valueless in my opinion. Why would you even do that. The heaters are to stabilize the oscillator. These units were used in fridged locations under extreme conditions.

[@charlessmith833]

I value your opinion but I do not consider the conversion a desecration any more than a teenager converting a vintage car into his dream mobile. I converted about two dozen tube radios into 100% solid state to show it could be done. Any old tube radio can now be converted to solid state. I broke the barrier. Nobody previous to me had that kind of success in converting tube radios. The attempts I have seen used very complex circuitry and never finished the job of converting the whole radio. Many hams hack radios without mercy with their "improvements". I did not do that. Tubes are getting extremely expensive, and some are very rare. In the near future you won't have any luck finding many of the tubes that used to be common. Everything has moved over to solid state lamentably. As far as the heaters go in the R390A, I gave you a choice to use them or not by supplying both wiring options. Not many hams live in Siberia or the north pole and if you live in Louisiana the heaters would cause you an extended warm up time every time you turned on the radio and you would have to wait patiently for the drift to settle down. I examined a couple of the heaters to see why they didn't work and found out that they are basically a piece of crap. Do as you wish but I will stand by my solid state radios to outlast the tube units as the years go by.