Post apocalyptic technology musings.
I'm a kid from the apocalypse era. You know, from when we just knew WW3 was just around the corner. The Cuban Missile Crisis was the worst part. Us kids in grade school were being taught to duck and cover when we saw the actinic flash of thermonuclear explosion. Scary times.
There certainly was enough post apocalypse science fiction being published back then. Heinlein's Farnham's Freehold was one I remember most. There a guy prepares for the main bang rather well. Ever since, I've kept a mental folder open on things to do after the sudden fall of modern civilization. Like how to get safe water, making do on beans and rice and big bottle of vitamin pills, how to sleep safe and warm and maybe hiking to find the remaining pockets of civilization. That's where two way radio comes in.
So after the big last war, we've got lots of junk and not many survivors, that means salvaging and cobbling up radios will be important. This is part of why I was interested in the 1632 series, since the Grantville folks were in an even worse position, a six mile sphere containing them dropped into 1632. There weren't any other pockets of near modern civilization, they were just surrounded by musket bearing, sword wielding near barbarians.
If I wanted to build a portable two way radio for back then, I'd start with what could be made from scrap broadcast radios and discarded TV sets. There won't be any transmitting power tubes in a town like Grantville, the biggest tubes around would be the horizontal output tubes in the old tube TV sets. The transistorized TVs wouldn't use good RF power transistors. The tubes give about 60 watts transmit power over a 15 to 30000 kHz. range. That would be enough to cover around 150 miles, ground wave. If you could make an antenna 250 high, you might extend that range to 500 miles using the AM broadcast band, 560-1800 kHz. But only at night. That's not very portable though.
The shortwave bands are pretty iffy, tough to predict with any certainty, but when conditions are right a small transmitter and good receiver can achieve ranges of many thousands of miles. I've personally chatted with hams in Japan, Australia and Pitcairn Island while driving home from work in Kansas City. My rig was a Uniden HR-2600 10 meter band mobile radio modified for 60 watts PEP and a receiver sensitivity of .05uV and the antenna was a terribly short one for the band, a whip antenna on top of my 1984 Honda Civic station wagon.
Could this sort of radio system be built in 1632 Grantville from scavenged parts? No way. The radio I was using was loaded with uncommon transistors, quartz crystals and integrated circuits. But if morse code is used, then maybe. With a 'gearing down' sort of design.
In 1635: The Eastern Front there were several battery operated 'tuna tin' two way radios (ones with transmitter and receiver in one package) in use by the military armies. First error, the Tuna Tin radio was just a transmitter, no receiver. Also the battery used wasn't possible in that era. By 1635, all the Grantville dry cell batteries would have become useless unless they were kept in the original packaging, I expect a shelf life of around five years. More if kept refrigerated. So they would have to be using locally made batteries, that's a tall order for 1635. Grantville technology might make a zinc/copper/acid battery possible, but it wouldn't be all that portable. The LeClanche derived dry cell needs zinc,manganese dioxide and sal ammoniac plus a carbon electrode and those materials would be available in 1635 but not in very pure form. If they were, then I think the cells would have to be about the size of C or D flashlight batteries.
The 1635 tuna tin radios had the batteries inside the can. Much too small for something the size of a tuna tin. About all that would fit would be a 9V transistor radio battery and those wouldn't have the power (200 mAh) for either any sort of range or lifetime (less than 5 hours) if it had to power both the receiver and transmitter. The original Tuna Tin transmitter had about 1/3 watt output and used 12 volts to get it from a 2N2222 transistor. With a 9V battery the transmitter power would be less, about 1/5 watt. Also the 2N2222 wouldn't likely be found in Grantville's junk radios. If a Grantville ham was also a circuit builder, he might have a bag of these on hand. They're very generic parts for builders, but not used in consumer products.
The next difficulty is quartz crystals. This is what makes a radio's frequency stable enough to be usable by non-experts. They were a critical resource in WW2. These would not be available in a form needed for radios in 1635, they need to be ground to precise thickness and have very flat and parallel faces. A lapidary expert might be able to make a few with 1635 technology, with time and help from Grantville knowledge. Precision grinding tables might be made that would give the parallel accuracy needed, but grinding to a specific frequency would be very, very difficult. Today it requires specialized oscillation test fixtures and precision frequency counters to check the grind all along the way. Making a matched pair would be really tough. But there may be way to get a few matched sets, grind one large plate then break it into two, four or more smaller sections, they'll all be very close to the same frequency and maybe that's enough for military use.
The next problem is capacitors. Good radio performance designs didn't come about until about 1920. They used thin layers of mica and metal foil, all contained in a sheet metal case. I think 1635 technology could make these, but getting a specific value would be a lot of trial and error and that means measuring equipment. Not going to be available in 1635, so it would be up to Grantville technologists to build it. Guys, the only fellows who might have a chance of this is the high school physics teacher or possibly the ham radio operator, but he'd be a very unusually advanced one. I suppose necessity could provide the impetus for the ham to advance himself.
The next problem is the coils. 1635 metal workers could draw copper the required size, if the copper was pure enough and had been annealed to be ductile and not brittle. But applying insulation would be a big problem. Wires in our early history were insulated with fabric woven over it. When winding into coils, fabric isn't good enough for radio. Vibration and friction will result in shorted turns that will clobber the performance. Early radio capable coils used wire with enamel insulation, oil based and not all that good since it turns brittle with age and softens with heat. Modern enamels use alkyd synthetics with urethanes. It's possible Grantville's chem guru, Tom "Stoner" Stone, might come up with something like that.
Finally we get around to transistors and diodes. There's no way 1635 technology or even Grantville tech can make these, so all that exists in this time frame is what Grantville brought with them. Once they're gone, that's it for at least 100 years. A hobby builder, the TV repair shop and personal consumer electronics might have these, enough to supply many two way Tuna Tin-ish two way radios, if the design is good enough. The principle information source for suitable designs would be in the Amateur Radio Relay League's Handbook, the older the better. By 2000 the ARRL had quit putting the old, simple designs in. Instead their circuits used special function ICs not found in consumer electronics instead of discrete parts.
So, could 1635 Ring of Fire armies have two way radios? Not likely, but if enough effort was made and luck was with them, yes.
Don't know if I should post this. I started it yesterday and forgot about it until I rebooted the laptop and started up Deepest Sender to post something else and there it was.
There certainly was enough post apocalypse science fiction being published back then. Heinlein's Farnham's Freehold was one I remember most. There a guy prepares for the main bang rather well. Ever since, I've kept a mental folder open on things to do after the sudden fall of modern civilization. Like how to get safe water, making do on beans and rice and big bottle of vitamin pills, how to sleep safe and warm and maybe hiking to find the remaining pockets of civilization. That's where two way radio comes in.
So after the big last war, we've got lots of junk and not many survivors, that means salvaging and cobbling up radios will be important. This is part of why I was interested in the 1632 series, since the Grantville folks were in an even worse position, a six mile sphere containing them dropped into 1632. There weren't any other pockets of near modern civilization, they were just surrounded by musket bearing, sword wielding near barbarians.
If I wanted to build a portable two way radio for back then, I'd start with what could be made from scrap broadcast radios and discarded TV sets. There won't be any transmitting power tubes in a town like Grantville, the biggest tubes around would be the horizontal output tubes in the old tube TV sets. The transistorized TVs wouldn't use good RF power transistors. The tubes give about 60 watts transmit power over a 15 to 30000 kHz. range. That would be enough to cover around 150 miles, ground wave. If you could make an antenna 250 high, you might extend that range to 500 miles using the AM broadcast band, 560-1800 kHz. But only at night. That's not very portable though.
The shortwave bands are pretty iffy, tough to predict with any certainty, but when conditions are right a small transmitter and good receiver can achieve ranges of many thousands of miles. I've personally chatted with hams in Japan, Australia and Pitcairn Island while driving home from work in Kansas City. My rig was a Uniden HR-2600 10 meter band mobile radio modified for 60 watts PEP and a receiver sensitivity of .05uV and the antenna was a terribly short one for the band, a whip antenna on top of my 1984 Honda Civic station wagon.
Could this sort of radio system be built in 1632 Grantville from scavenged parts? No way. The radio I was using was loaded with uncommon transistors, quartz crystals and integrated circuits. But if morse code is used, then maybe. With a 'gearing down' sort of design.
In 1635: The Eastern Front there were several battery operated 'tuna tin' two way radios (ones with transmitter and receiver in one package) in use by the military armies. First error, the Tuna Tin radio was just a transmitter, no receiver. Also the battery used wasn't possible in that era. By 1635, all the Grantville dry cell batteries would have become useless unless they were kept in the original packaging, I expect a shelf life of around five years. More if kept refrigerated. So they would have to be using locally made batteries, that's a tall order for 1635. Grantville technology might make a zinc/copper/acid battery possible, but it wouldn't be all that portable. The LeClanche derived dry cell needs zinc,manganese dioxide and sal ammoniac plus a carbon electrode and those materials would be available in 1635 but not in very pure form. If they were, then I think the cells would have to be about the size of C or D flashlight batteries.
The 1635 tuna tin radios had the batteries inside the can. Much too small for something the size of a tuna tin. About all that would fit would be a 9V transistor radio battery and those wouldn't have the power (200 mAh) for either any sort of range or lifetime (less than 5 hours) if it had to power both the receiver and transmitter. The original Tuna Tin transmitter had about 1/3 watt output and used 12 volts to get it from a 2N2222 transistor. With a 9V battery the transmitter power would be less, about 1/5 watt. Also the 2N2222 wouldn't likely be found in Grantville's junk radios. If a Grantville ham was also a circuit builder, he might have a bag of these on hand. They're very generic parts for builders, but not used in consumer products.
The next difficulty is quartz crystals. This is what makes a radio's frequency stable enough to be usable by non-experts. They were a critical resource in WW2. These would not be available in a form needed for radios in 1635, they need to be ground to precise thickness and have very flat and parallel faces. A lapidary expert might be able to make a few with 1635 technology, with time and help from Grantville knowledge. Precision grinding tables might be made that would give the parallel accuracy needed, but grinding to a specific frequency would be very, very difficult. Today it requires specialized oscillation test fixtures and precision frequency counters to check the grind all along the way. Making a matched pair would be really tough. But there may be way to get a few matched sets, grind one large plate then break it into two, four or more smaller sections, they'll all be very close to the same frequency and maybe that's enough for military use.
The next problem is capacitors. Good radio performance designs didn't come about until about 1920. They used thin layers of mica and metal foil, all contained in a sheet metal case. I think 1635 technology could make these, but getting a specific value would be a lot of trial and error and that means measuring equipment. Not going to be available in 1635, so it would be up to Grantville technologists to build it. Guys, the only fellows who might have a chance of this is the high school physics teacher or possibly the ham radio operator, but he'd be a very unusually advanced one. I suppose necessity could provide the impetus for the ham to advance himself.
The next problem is the coils. 1635 metal workers could draw copper the required size, if the copper was pure enough and had been annealed to be ductile and not brittle. But applying insulation would be a big problem. Wires in our early history were insulated with fabric woven over it. When winding into coils, fabric isn't good enough for radio. Vibration and friction will result in shorted turns that will clobber the performance. Early radio capable coils used wire with enamel insulation, oil based and not all that good since it turns brittle with age and softens with heat. Modern enamels use alkyd synthetics with urethanes. It's possible Grantville's chem guru, Tom "Stoner" Stone, might come up with something like that.
Finally we get around to transistors and diodes. There's no way 1635 technology or even Grantville tech can make these, so all that exists in this time frame is what Grantville brought with them. Once they're gone, that's it for at least 100 years. A hobby builder, the TV repair shop and personal consumer electronics might have these, enough to supply many two way Tuna Tin-ish two way radios, if the design is good enough. The principle information source for suitable designs would be in the Amateur Radio Relay League's Handbook, the older the better. By 2000 the ARRL had quit putting the old, simple designs in. Instead their circuits used special function ICs not found in consumer electronics instead of discrete parts.
So, could 1635 Ring of Fire armies have two way radios? Not likely, but if enough effort was made and luck was with them, yes.
Don't know if I should post this. I started it yesterday and forgot about it until I rebooted the laptop and started up Deepest Sender to post something else and there it was.