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tube fanatic

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  1. Perhaps an antenna in the attic can collect a nearby static discharge but if it takes a direct strike you got bigger problems.

    That's quite correct. Even a nearby thunderstorm (or snowstorm) can induce charges of hundreds of volts in antennas regardless of where they are mounted. To think of having any kind of antenna installation which is not protected is a mistake. A properly designed discharge unit constantly drains all induced voltages to ground (as opposed to those which don't discharge until a predetermined voltage is present) which makes the antenna less "attractive" to the step leader which preceeds the lightning strike itself. These units are not only grounded, but also bonded to the ground system of the building's electrical service, telephone service, and if copper plumbing is present to that as well. There are many sites which discuss the correct way to install lightning protection for antennas including Polyphaser's and ICE's.

  2. Lightning just burns out the braid on the co-ax, whether or not it's grounded.

    _Sometimes_ what it was hooked to can be repaired.

    djk is quite correct. A direct hit to the antenna would vaporize the antenna and the connected coax. But, in the process, many kilovolts would pass through the coax into any connected equipment, and possibly into the house wiring. The devices by Polyphaser and ICE are designed to prevent such connected equipment from that event when installed correctly. That is why the coax needs to be brought outside the house to ground level for connection to the protective device. A number of ham operators I know have taken direct hits to their tower mounted antennas (in some cases at 75-100 feet above ground), but the connected equipment remained intact!

  3. Grounding is not necessary to protect from lightning simply because it will not protect anything if you get a direct lightning strike. The only thing that would protect against something so catestrophic is a home lightning rod system. You are better off not grounding so it does not introduce a ground loop into your system.

    The correct way to do it, if you want lightning protection, is to bring the coax outside the house (possibly through the gable vent, or a small hole) and take it to ground level where it can be attached to a properly designed and installed lightning arrestor (such as available from Polyphaser or Industrial Communications Engineers). The coax coming out of the arrestor can then be routed back into the house as desired. As stated above, attic mounting does not offer protection from a direct hit, so if you are in a high lightning area you are taking a big chance. Additionally, if the grounding of the antenna is properly executed, you will have no ground loop problems.

  4. You guys are going to throw daggers at me for saying this, but the differences in the sound of interconnects is usually related to the capacitance of the cables- it's not the fancy gold-plated plugs, or the silver plated copper wire, etc. This can be easily tested yourself if you are handy with a soldering iron by buying lengths of various coaxial cables, putting on your own RCA plugs, and then sitting down to listen. The chart found on the site below shows the capacitance of various coaxial cables which you can use as a guide. They are available from the major electronics suppliers like Allied, Newark, and Mouser (Radio Shack even has some). Some local audiophiles and I have tried many blind listening tests in which we compared the sound of some very expensive cables with our home-made cables, and the results were not what one would have expected (the megabuck cables often came in last)! Try it and post your results........

    http://www.rfcafe.com/references/electrical/coax-chart.htm

  5. For that price I'd grab it! But, bear in mind that it may be way out of calibration in spite of the claim that it works perfectly. The calibration info for it is readily available, so you can always bring it to a technician to have it brought up to spec.

  6. The most important question before considering the S-5000 is whether it has been restored or not. Amps of that vintage usually need to have many capacitors replaced, the output stage bias checked and readjusted, controls checked/cleaned/lubricated, and lots more! Also, what is the condition of the tubes? If memory serves, some of the S-5000s used 7868s in the output stage- real expensive if they need replacement. Are you considering buying it from a reputable dealer/restorer who will give you some kind of warranty? The bottom line is if it is working properly it should sound terrific. But frankly, with K-horns you would probably be better off with a nice, new low powered triode amp. Unless you are into extremely high sound pressure levels, 3-5 watts is more than enough with those speakers.

  7. Be careful if you purchase a used player as you have no idea how much abuse the transport has taken. We had many come through the shop which were supposedly "minimally used," only to develop transport problems shortly after. To me, it isn't worth taking the chance unless you know the person you are purchasing from.

  8. If your dad doesn't mind a changer, the Sony SCD-CE595 is an incredible value for a street price of around $125. The sound of this unit is beyond phenomenal and approaches that of my friend's Wadia Model 6, one of the best sounding CD players ever made. Buy from a place like J & R music and you can return it if not satisfied. I've used one as a source when designing and restoring tube amps and it has never taken me in the wrong direction!

  9. I haven't worked on a 500C in too many years to recall if the numbers, etc, are baked on enamel or decals. If it's enamel you can just wipe it with a paper towel moistened with some Windex or similar. If decals, you need to lightly moisten a q-tip with some Windex and clean around them without getting the decals overly wet. It's painstaking work, and you will need a few dozen q-tips, but it can be done. I've used these methods to clean the dial glasses of a few hundred antique radios and it works out quite well.

  10. Well, the Isoblok above is rated for 600j. I live in a very high lightning strike area and have never had one fail, nor has anything plugged into one failed either. You can buy spike suppressors that go up into the thousands of joules; whether you need that much protection is hard to say. But, for a few dollars more you can get a similar plug-in unit which is rated for around 1400j:

    http://www.tripplite.com/en/products/model.cfm?txtSeriesID=74&EID=345&txtModelID=3980

    You also need to consider the clamping voltage, or the voltage at which suppression becomes effective. Some units out there clamp at over 300 volts whereas these clamp at 140 volts. You want the clamping voltage to be as low as possible.

  11. Transformers are made with different types of insulation- some can safely run at hotter temperatures than others. Do you know the manufacturer of this particular transformer? If so, you can contact them to obtain the necessary info. If you are concerned, why not use a small and quiet running muffin fan to dissipate the heat somewhat. All the components will be grateful for that.

  12. Be careful if you buy an Eico as many were sold as kits and may not have been well constructed (i.e. poor solder joints, overheated components, etc.). Also, depending on age, many will need to be restored by replacing out of spec resistors, replacing all the capacitors, and then being recalibrated..............

  13. With tube amps, due to the relatively high output impedance, you need to use short connections to the speakers or you will notice definite frequency response differences. Given the 30 foot run from the amps to your source components in the studio, be sure to use very heavily shielded cables to avoid hum and noise pickup.

  14. Well, if you really want one, definitely follow the advice above from dbspl and get a Hickok. But, be absolutely sure you can get hold of the calibration info for it to verify its accuracy. If it isn't properly set you may think that the tubes you are testing are great when in fact they aren't.

  15. A tube tester will only drive you nuts! If your output tubes bias correctly, and sound wonderful, do you care if the tube tester says that they aren't good? Triodes like the 12AX7 are capable of delivering fine sound over such a wide range of operating conditions that testing them is a moot point if they sound good. A better approach for the triodes is to use the eraser end of a pencil to gently tap the tube while in operation to check for microphonics (the sound of your tapping being audible in the speakers). Choosing different 12AX7s based on doing that simple test is more valuable and can result in noticeable improvements in the sound.

  16. There's absolutely no need to spend much money on fancy cables. Differences in sound between cables is directly related to slight differences in the cable capacitance. If you're fairly handy with a soldering iron you can make fabulous cables with inexpensive coaxial cable such as RG-58, RG-8X, etc, and cheap RCA plugs. They will rival the performance of cables which cost thousands of dollars!

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