I have an old homemade broadcast radio from the early 20s wired with the variometer as the feedback, and the fixed winding as antenna. It uses the variometer as the regen control. It covers down below 500 kc up to about 1500 kc in one shot. It only has tuning, regen, and filament controls, no antenna trim. It works ok, as long as the converter tube can oscillate.
I built a Philmore regen kit from small Lafayette chain store, as a kid, that probably had a coil out of phase. It and never oscillated. Thanks for dwelling on this idea Mike.
Thanks for the video Mike, we are so fortunate today that we have gadgets like the Nano VNA to make coils to get us to the baseline before adding or subtracting turns in order to get the coil to suit frequency in conjunction with the other components.
Modeling, online calculators, old time equipment like grid dippers and Q meters and LCR meters all have their place. But the VNA, now available to the average experimenter at a modest price, is a game changer to opening up the mysteries and practical limitations of RF design with real world components.
"Maybe it's repairable." Yep. I fixed my bench Fluke multimeter for nothing by tearing the outer insulation off the power transformer and getting down to the blown internal fuse. It was an Air Force meter I got from a government scrap sale for next to nothing because it had a repair depot tag on it that said, "Unrepairable." It's now worked fine for the last 20 years. This guy clearly built the rig out of junkbox parts. Parts were harder to find back in the day, especially for rural youngsters. I'm now fortunate to live in a city with a lot of tech start-ups and dumpsters, and a couple of ham swaps every year.
In the 1920s, several resellers listed Samson Electric Co's No. 125 RF choke as 125 mH while others listed it as 250 mH. Luckily, Samson themselves advertised in Radio Broadcast for December 1926; they gave its value as 250 mH.
Looks like coil forms and sockets are still quite reasonable on eBay (some of them brand new from China). I'm retiring "soon", it may be time to get a few of these so I can start to work on my own multi-band regen. Got a few tubes around, but no junk box, so I'll need to either grab a couple "for parts" radios off eBay or prowl the local thrift stores and see if they have anything with tubes inside. Might have to revise my watch list, though, to get 5- or 6-pin forms and sockets, so I can put triple coils on the forms.
That red stuff looked like sealing wax. It wasn't made only from wax but also contained resin. Maybe touch it with a soldering iron and check the smell.
Yeah, sealing wax or laboratory "Faraday wax". No experimenter in their right mind hard pots things like this, I'm not sure such hardening resins were commonly available or used at that point, my understanding is most potted electronics of the time were potted in tar.
I started in electronics back in 1962 at 12 years old, and done electronics for a living ever since, working at HP, TRW, IBM, SONY, etc over the years. But whenever I start getting a big head about my radio knowledge I just come to your channel or the Mr. Carlsen's Lab channel and I'm a noob again.
Thank you Sir. I love your channel!! I had old timers/Elmer's..and minus humming flouro lights and gas/lawnmower old garage smells.. I'm back to a young lad of 10 💪🇺🇸
Thank you mike for all the pointers on regen s. If you say two different coils are needed to cover the whole AM broadcast band, then why does these regens radios only use one coil, the Knight "Spanmaster" uses 1 coil to cover .54 to 1.7 mhz, knight "Ocean Hopper" covers .53 to 1.9mhz, Knight Space Spanner covers .54mhz to 1.7mhz? And the Heathkit uses 2 coils one for longwave 140 to 560 khz and 2nd coil for standard BC 560 to 1750 khz? Can you explain why these sets only need one coil to cover the whole AM BC band, is it due to using a dual 365 pf tuning cap (or a 400 pf in the Knight Spanmaster)? I can see that a 140pf cap does not have enough range for AM BC band, is that why 2 coil requirement if your intending to cover SW too? It's apparent you don't really have to have two coils to cover the AM BC band.
Certainly, if the set specified a lower value cap like a 200 pF, this would improve SW performance, but that would c require two coils. It depends on the self resonance of the plug in coils. Scramble winding and litz wire would help. With a normal 365 pF variable, I have never been able to cover the entire band. You would get there with two sections.
@@MIKROWAVE1 I wonder if you use a ferrite rod to make one regen coil, that can cover the AM broadcast band. You should be able to space the primary winding (and fewer turns) to raise the self resonance by lowering self capacitance. With less wire required to obtain the same inductance you should wind up having a higher Q coil.
@@JCWise-sf9ww I have two regen that will take the same BCB coils. One has a standard half moon 365 you can still get and one big brass Pilot that has a fancy orthometric cut. Lets see which one does better.
@@MIKROWAVE1 Mike, I guess we have to put together a regenerative circuit to see what happens, I believe what your trying to say has something to do with linearity making tuning touchy at one end.
I just tried the "high" plug in coil on the original Morgan. I could tune the entire band but I had to adjust the antenna coupling trimmers from fully closed to almost fully open to do it. My other regen with the big brass variable easily hit the entire band, but it is a much better capacitor and has a higher mesh capacitance. With the "low" plug in coil it could go all the way down to 400 kHz.
I have an old homemade broadcast radio from the early 20s wired with the variometer as the feedback, and the fixed winding as antenna. It uses the variometer as the regen control. It covers down below 500 kc up to about 1500 kc in one shot. It only has tuning, regen, and filament controls, no antenna trim. It works ok, as long as the converter tube can oscillate.
Well done Mike! Thanks and 73.
Mike, great info it helps a regenerative nut, 73, tks !
Ah yes - the Regenerative Nut!
I built a Philmore regen kit from small Lafayette chain store, as a kid, that probably had a coil out of phase. It and never oscillated. Thanks for dwelling on this idea Mike.
I have a Meissner Regen Kit with plug in coils that I restored, that a buddy has now. It was an AC/DC widowmaker!
Thanks for the video Mike, we are so fortunate today that we have gadgets like the Nano VNA to make coils to get us to the baseline before adding or subtracting turns in order to get the coil to suit frequency in conjunction with the other components.
Modeling, online calculators, old time equipment like grid dippers and Q meters and LCR meters all have their place. But the VNA, now available to the average experimenter at a modest price, is a game changer to opening up the mysteries and practical limitations of RF design with real world components.
@@MIKROWAVE1 The VNA is truly a blessing and good education tool for beginners like me.
A lot of great information on multiple aspects to get a Regen operating!
"Maybe it's repairable." Yep. I fixed my bench Fluke multimeter for nothing by tearing the outer insulation off the power transformer and getting down to the blown internal fuse. It was an Air Force meter I got from a government scrap sale for next to nothing because it had a repair depot tag on it that said, "Unrepairable." It's now worked fine for the last 20 years.
This guy clearly built the rig out of junkbox parts. Parts were harder to find back in the day, especially for rural youngsters. I'm now fortunate to live in a city with a lot of tech start-ups and dumpsters, and a couple of ham swaps every year.
That's my favourite supplier 🤣
In the 1920s, several resellers listed Samson Electric Co's No. 125 RF choke as 125 mH while others listed it as 250 mH. Luckily, Samson themselves advertised in Radio Broadcast for December 1926; they gave its value as 250 mH.
Wow, that is very excessive for SW. That would be ideal for Longwave in a regen.
Looks like coil forms and sockets are still quite reasonable on eBay (some of them brand new from China). I'm retiring "soon", it may be time to get a few of these so I can start to work on my own multi-band regen. Got a few tubes around, but no junk box, so I'll need to either grab a couple "for parts" radios off eBay or prowl the local thrift stores and see if they have anything with tubes inside. Might have to revise my watch list, though, to get 5- or 6-pin forms and sockets, so I can put triple coils on the forms.
Plug In coils are a fun challenge, and well worth taking on with retirement!
That red stuff looked like sealing wax. It wasn't made only from wax but also contained resin. Maybe touch it with a soldering iron and check the smell.
Yeah, sealing wax or laboratory "Faraday wax". No experimenter in their right mind hard pots things like this, I'm not sure such hardening resins were commonly available or used at that point, my understanding is most potted electronics of the time were potted in tar.
@@Broken_Yugo It was a mobile device, maybe it makes sense to ruggedize it.
I started in electronics back in 1962 at 12 years old, and done electronics for a living ever since, working at HP, TRW, IBM, SONY, etc over the years. But whenever I start getting a big head about my radio knowledge I just come to your channel or the Mr. Carlsen's Lab channel and I'm a noob again.
I have NOS of that beat up choke like a 50 of them
They are precious items.
Would a grid dip meter be helpful with the trial and error method of winding a plugin coil?
Absolutely! Several other methods would help with resonance too, but the mutual coupling is more difficult to predict.
Thank you Sir. I love your channel!! I had old timers/Elmer's..and minus humming flouro lights and gas/lawnmower old garage smells.. I'm back to a young lad of 10
💪🇺🇸
Thank you mike for all the pointers on regen s. If you say two different coils are needed to cover the whole AM broadcast band, then why does these regens radios only use one coil, the Knight "Spanmaster" uses 1 coil to cover .54 to 1.7 mhz, knight "Ocean Hopper" covers .53 to 1.9mhz, Knight Space Spanner covers .54mhz to 1.7mhz? And the Heathkit uses 2 coils one for longwave 140 to 560 khz and 2nd coil for standard BC 560 to 1750 khz? Can you explain why these sets only need one coil to cover the whole AM BC band, is it due to using a dual 365 pf tuning cap (or a 400 pf in the Knight Spanmaster)? I can see that a 140pf cap does not have enough range for AM BC band, is that why 2 coil requirement if your intending to cover SW too? It's apparent you don't really have to have two coils to cover the AM BC band.
Certainly, if the set specified a lower value cap like a 200 pF, this would improve SW performance, but that would c require two coils. It depends on the self resonance of the plug in coils. Scramble winding and litz wire would help. With a normal 365 pF variable, I have never been able to cover the entire band. You would get there with two sections.
@@MIKROWAVE1 I wonder if you use a ferrite rod to make one regen coil, that can cover the AM broadcast band. You should be able to space the primary winding (and fewer turns) to raise the self resonance by lowering self capacitance. With less wire required to obtain the same inductance you should wind up having a higher Q coil.
@@JCWise-sf9ww I have two regen that will take the same BCB coils. One has a standard half moon 365 you can still get and one big brass Pilot that has a fancy orthometric cut. Lets see which one does better.
@@MIKROWAVE1 Mike, I guess we have to put together a regenerative circuit to see what happens, I believe what your trying to say has something to do with linearity making tuning touchy at one end.
I just tried the "high" plug in coil on the original Morgan. I could tune the entire band but I had to adjust the antenna coupling trimmers from fully closed to almost fully open to do it. My other regen with the big brass variable easily hit the entire band, but it is a much better capacitor and has a higher mesh capacitance. With the "low" plug in coil it could go all the way down to 400 kHz.