Home |
Search |
Today's Posts |
|
#1
|
|||
|
|||
I don't know if the NCX-5
was solid state but it was from the tube era. Both the NCX-5 and -3 use a separate AC power supply, and the original poster wants it all in one box. Nice rigs though. --Mike K. Oscar loves trash, but hates Spam! Delete him to reply to me. |
#2
|
|||
|
|||
I think I mentioned elsewhere in these discussions that the main reason I'm looking for an all-tube SSB/CW transceiver is for when (not "if", unfortunately) terrorists manage to smuggle a nuclear weapon into this country and set it off. (Hell, no, I'm not paranoid, which one of my enemies told you that?) :-( I'm looking for something that has a reasonable chance of surviving the resulting EMP, and that means tube gear. Now, someone else here said something about the KWM-2 having germanium diodes in the balance modulator. Those aren't likely to survive any meaningful EMP (they can't even survive a little heat from a soldering iron, for Pete's sake) so that seems to let the KWM-2 out of the running. Of the other tube rigs mentioned ... Swan 260/270/350/500, Heath SB100/101 and HW-100 (also HW-101?), Hallicrafters SR-150, NCX-5, etc. .... how many of them have germanium diodes here and there that are likely to get smoked? What other considerations are there that would rule one of these other rigs in or out? Rick WA1RKT |
#3
|
|||
|
|||
snip What other considerations are there that would
rule one of these other rigs in or out? Rick WA1RKT ....probably the fact that if you are close enough to a nuclear blast which wipes out your gear due to EMP, the least of your worries will be whether or not your radio works. Just a thought... Barry - N4BUQ |
#4
|
|||
|
|||
|
#5
|
|||
|
|||
Rick,
Well thought out, but I think my response was meant more than just the results if you are near enough to the event to cause you direct harm. If such an event occurred and a majority of the solid-state devices are cooked, will your immediate concenrs be a radio? Who are you going to talk to or listen to? It seems the resulting chaos from such a scenario would make the fact of whether or not you have a working short-wave radio not very important. Again, just some thoughts... Barry - N4BUQ ...probably the fact that if you are close enough to a nuclear blast which wipes out your gear due to EMP, the least of your worries will be whether or not your radio works. Good afternoon, Barry. From the best my limited knowledge and aptitude on the topic has been able to determine over the last couple of weeks of research, that's probably not entirely accurate. A lightweight nuclear blast high up in the atmosphere can wipe out equipment for hundreds to a thousand miles around. Lower-altitude blasts have a lesser range of damage, but my guess (and it's only a guess) is that a 50-kiloton device on the observation deck of the Empire State building would result in EMP damage far outside of the range of heat and blast destruction. If someone set off such a device at the top of the Prudential Center or John Hancock Tower in Boston, chances are pretty good that my computers, telephone, cell phone, modern solid-state ham gear, not to mention the electrical power, would all be pretty well destroyed here in southern New Hampshire, but we probably wouldn't get any blast or heat damage to speak of. There would be time to load my old tube gear (which I don't have yet) into my motorhome and get outta Dodge, assuming the engine-control computer in my motorhome didn't get smoked (which it probably would, though I don't know how much of that type of high-techie stuff they put in Toyotas in 1990 so maybe not...). Rick WA1RKT |
#6
|
|||
|
|||
|
#7
|
|||
|
|||
|
#8
|
|||
|
|||
The EMP problem is very well studied, and very classified. You
won't find much detailed information. The US has spent billions of dollars studying it. The amount of money spent should act as an indicator of the danger of the effect. EMP is far worse than lightning! This is because the risetime of EMP is in the sub pico second region. Even a dead short circuit looks like an inductor at these frequencies. Now, on the bright side, all of the IC manufacturers have been hardening their ICs for electro static and EMP effects for at least the last 20 years. They know the score, and don't want their stuff fizzling with EMP. EMP hardened pads cost them nothing to include. As to tube gear surviving EMP, every commercial tube rig made in the '60s and 70s had some solidstate in it. The HW101 had a solid state LTO, the HW100 was tube, with a varactor to shift the vFO for usb/lsb. Same with the SB100/101. SB102 had a ss LTO. Diodes were used here and there to aid in T/R switching.... If spamsink is really interested in having a rig that will survive EMP he should look at some of the US military solid state gear. It is all hardened. Or, on a cheaper note, put an ICOM in a copper can. -Chuck, WA3UQV ckh wrote: On Sun, 7 Sep 3903 14:51:24, wrote: I think I mentioned elsewhere in these discussions that the main reason I'm looking for an all-tube SSB/CW transceiver is for when (not "if", unfortunately) terrorists manage to smuggle a nuclear weapon into this country and set it off. (Hell, no, I'm not paranoid, which one of my enemies told you that?) :-( |
#9
|
|||
|
|||
"Chuck Harris" wrote in message ... The EMP problem is very well studied, and very classified. You won't find much detailed information. The US has spent billions of dollars studying it. The amount of money spent should act as an indicator of the danger of the effect. EMP is far worse than lightning! This is because the risetime of EMP is in the sub pico second region. Even a dead short circuit looks like an inductor at these frequencies. Now, on the bright side, all of the IC manufacturers have been hardening their ICs for electro static and EMP effects for at least the last 20 years. They know the score, and don't want their stuff fizzling with EMP. EMP hardened pads cost them nothing to include. As to tube gear surviving EMP, every commercial tube rig made in the '60s and 70s had some solidstate in it. The HW101 had a solid state LTO, the HW100 was tube, with a varactor to shift the vFO for usb/lsb. Same with the SB100/101. SB102 had a ss LTO. Diodes were used here and there to aid in T/R switching.... If spamsink is really interested in having a rig that will survive EMP he should look at some of the US military solid state gear. It is all hardened. Or, on a cheaper note, put an ICOM in a copper can. -Chuck, WA3UQV One of the best RF shielded structures is available for a couple of dollars at your local hardware store. Just buy a couple of 1 gallon steel paint cans. Drop in your survival radio and a battery, and tap the top back on. (A true survivalist would also can a good revolver and a couple of boxes of ammo; not for NEMP protection, just for convenience.) The mechanical wiping interference fit of the lid makes for an excellent RF shield. Watch out for some cans with an internal plastic film; either get the metal plated cans, or buff off the plastic film from the can and lid seal faces. The scenario for NEMP is 50,000 volts per meter electric field strength at the Earth's surface. If you want to protect your equipment from this threat, then you have to treat every interface to your rig. That means shielding the case and filtering / limiting the power cable, any computer I/O lines, any external meters or speakers, and the antenna cable. The easiest way to do all this is to put the rig, plus speakers and meters, into a very conductive box (Faraday cage). Use a powerline filter with transient limiters to bring power into the box. Use a fast-acting limiter (designed with NEMP in mind) on the coax. Provide ventilation through honeycomb or multiple small diameter holes. By now, you may have noticed that although the rig is protected, you have created a very difficult to use station. OK, just make your shielded box bigger, and climb inside. A decent home-made shielded box should easily give you 80 dB or so of shielding effectiveness, which is a 10,000x reduction, thus exposing the rig to only 5 V/M of the 50,000 V/M NEMP. Remember that you are only protected when the access door is properly closed. It won't do any good if you do everything else correct, but leave the door hanging open an inch. Finally, a note about military gear. Not all mil equipment is procured to the same performance level. Since shielding and other protection adds weight, bulk and cost, some mil equipment is built tougher than other mil equipment. An RF transponder used in a submarine has less need for NEMP hardening (the sub hull and the water provide a lot of shielding) than a composite airframe missile. OTOH, what are the odds of a missile being in-flight during a nuclear event? (Harden the launcher box, not the vehicle itself.) So, although any mil equipment is more likely to survive an NEMP than civilian stuff, some mil stuff is a lot better than other mil stuff. If you are buying surplus mil gear, consider the original mission scenario and the threats to that mission. Ed WB6WSN |
#10
|
|||
|
|||
On 7 Sep 2003 20:22:34 GMT, Too Much SPAM (ckh) wrote:
Or it could mean that you keep a backup, inexpensive solid state rig in a metal box. It could be anything, an old Tentec, an IC-701, anything will work. My so-far-limited research indicates that probably wouldn't be good enough. You'd have to have more than just a thin metal box, maybe a THICK metal box, or lead, or something, and perhaps there'd be grounding considerations. If you planned for it, you could have a spare set of diodes in the impervious metal box and just sub them in when the balloon goes up. True, I thought of that, and it's one of the options. Anyway, I'm guessing that the EMP risk is overstated. I would like to think so, but I don't, not really... there is a lot of information out there that seems to indicate it's a real danger. Rick WA1RKT |
Reply |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
The "TRICK" to TV 'type' Coax Cable [Shielded] SWL Loop Antennas {RHF} | Antenna | |||
Needed: Recommendations for coax for VHF and UHF work | Antenna | |||
Keeping moisture out of 9913 type coax? | Antenna | |||
New Type of HF Shootout (antennas, pedestrian, bicycle) | Antenna |