|KT8K posted on March 17, 2009:|
"Actually "De-Ox-Id" is a spray contact cleaner from electronic-related products supplier General Cement, is relatively inexpensive, and was once widely available among electronic parts sellers (most long gone). "De-Ox-It", on the other hand, is a high-end contact cleaner from CAIG. I have used both, and far prefer the CAIG products, but the GC cleaner does work. I just found that in some applications I had to be ready to re-apply it every 6-12 months. The CAIG product, while much more expensive, has never required me to re-apply it."
I will agree with you, Tim, and have to note I grew up in the town where GC began. :-)
I used GC "contact cleaner" (name before the better commercial product came out) decades ago as an ardent hobbyinst and once-in-awhile part-time TV repair money-grubber. It was never formulated for 'long life' by the original chemical formulator (GC repackages a lot of things buying other companies' products in bulk). Its 'cleaning action' is primarily as a lubricant which, accompanied by an unpleasant odor, make the user THINK they are cleaning something.
On the other hand, from listening to a lot of folks in the entertainment business, primarily in 'post-production houses' in/around Los Angeles (over 300 last I heard), the CAIG products are long-lived with little need to re-apply their cleaners. To explain, older audio mixing consoles would have multiple-contact continuously-rotating (no mechanical indexing) 'potentiometers' carrying low-level audio.* Contact noise would be readily apparent if it was there. Post-production companies in a very competitive market couldn't afford to spend time 'fixing' noisy audio (later video) electronics. While the ancient (pre-WWII) rotary gain controls were nearly always sealed, the in-line 'slider' types were more open by their control tab slot (seals would eventually wear out before any contacts got bad). Folks around here in the entertainment capital of the world don't want to fool with 'mouse milk' products (except for the Disney company) that don't do their job. That's where CAIG and a few of their contemporaries stepped in with superior products.
* Those old Pro gain controls are very-limited-application 'potentiometers' originated in motion picture sound production early in the 1930s, spread quickly to audio broadcasting and phonograph disc recording to become a mainstay of 'gain riders' controlling audio. They have fixed resistors and lots of multiple taps, each tap having multiple contacts on rotors, with the resistors usually in Tee configurations for low impedances (typically 600 Ohm in/out), contact metal alloys picked for a compromise of minimum oxidation and wear. They would usually outlast the employment time of any gain-rider using them. Costly, a single replacement gain control would cost more than a new retail-price Hallicrafters S-38 back when Halligan's company introduced that receiver. Some of those same gain controls are still alive and working today in broadcasting and recording. S-38s are now 'operating' on e-bay.
GC products were once 'popular' (their name known) with hobbyists because they were relatively CHEAP and distributed through 'radio parts stores' and had lots of advertising in radio/TV magazines. Only a few GC products are, in my opinion, worth their price: A fine design wire stripper flawed only by inattention to quality control on a spring (I had two, both with the same spring break failure); Corona dope, fine for 15 KV and up lines but displaced by much lower voltage display technology; 'Strip-X' one of the easiest-to-use magnet wire de-enamelizers ever, not permitted to be shipped out-of-state by later 'health laws' on chemical formulations that were supposedly terribly Terribly toxic, deadly Deadly Dangerous for shippers. Well, their old alignment tools are okay...those are inert but they don't get a lot of use either. Sort of like Greenlee chassis punches (another company from my home town). :-)
73, Len AF6AY
Reply to a comment by : KT8K
on 2009-03-17Actually "De-Ox-Id" is a spray contact cleaner from electronic-related products supplier General Cement, is relatively inexpensive, and was once widely available among electronic parts sellers (most long gone). "De-Ox-It", on the other hand, is a high-end contact cleaner from CAIG. I have used both, and far prefer the CAIG products, but the GC cleaner does work. I just found that in some applications I had to be ready to re-apply it every 6-12 months. The CAIG product, while much more expensive, has never required me to re-apply it.
That's just my experience - nothing scientific about it - but I thought I'd fill in as K1DA seemed confused by the *very* similar product names.
Best rx & 73 to all de kt8k - Tim
Reply to a comment by : K7PEH
I made a typo in attributing your question to 'K7PCH' and want to note that. My apologies.
No problem-o Len --- I appreciated your answer just as much with a small error in my call sign.
phil, K7PEH (actually, my initials so it is easier for me to remember)
Reply to a comment by : K6LHA
on 2009-03-16I made a typo in attributing your question to 'K7PCH' and want to note that. My apologies.
Reply to a comment by : K6LHA
on 2009-03-15K7PCH posed the question "why are switches sealed like this?" on 14 Mar 09:
The most obvious answer is to keep any sort of garbage out of the contact area, such as stray clippings of wire or other metal OUT. The other answers are subtle and have to do with the design of the rotary switch and the design of the equipment that uses it. To expand on the latter requires some explanation of the old, 'standard' rotary switch, such as the Centralab rotary switch line with (once upon a time) having wafers with 2 to 11 positions, 1 to 4 poles, shorting contacts or break-before-make contacts. All sorts of choices and they came in paper-phenolic dielectric or ceramic dielectric. All of those old, 'standard' switches had contacts fully open, unprotected and one could not stack wafers together, only through long pairs of screws with wafer-separation insulating tubes.
More-innovating manufacturers such as CTS (one example, formerly Chicago Telephone Supply corporate name) took on the thin-wafer, connection lugs in-line, sealed or semi-sealed wafer design after WWII. CTS was semi-sealed in that it had some relief holes in the rotor area, something like 10 to 20 percent (if memory serves). Instead of using eyelets to fasten stator contacts to the outer dielectric part of a switch wafer, the sealed switch makers molded-in the stator contact set and the exterior wire connection lugs with the main switch wafer body. After molding it was a very integral unit, quite 'one-piece.' Rotor contacts were in their own dielectric carrier (CTS stock design had clear plastic, main body grey). End result for any stack of wafers in any rotary switch assembly was a compact although flexible design that suited many applications, particularly range and function switches in the semiconductor test set plug-ins that I designed at Birtcher Instrument Division in Monterey Park, CA. With repeatable, flat-plane contact arrangements, they were just a tiny bit better suited for higher frequencies than the old, standard, all-open-to-the-elements designs that began in the 1930s. Grayhill (among a few others) survived the eventual demise of multi-wafer rotary switch combinations of olden times; Grayhill's design is very sealed.
The thinner, sealed rotary switch is better for piece-work production assembly in that all connections are in the same plane as the wafer, wires can hook though them a bit better than on old-design angled lugs. There are fewer errors from metal particle shorting that require extra labor-time repair on a production line. Setup costs for the old-design rotors were still less than for new, sealed-wafer designs but only 10 to 20 percent less. That could be amortized and offset by less labor for production line rework, something dear to manager's hearts. :-)
I should note that range and function switch subassemblies could be obtained with nice, compact mounting of resistors or capacitors between wafers and took the least time to design than the old, standard rotaries which required juggling wafer-separation tube sections made in odd fraction, limited sizes (for ceramic wafers). The sealed switch units looked better to anyone investigating the insides of a product in detail, another selling-point to customers. Silver-plating of rotary switch contacts were much more prone to long-term oxidation than the sealed-switch designs. For that matter, rotary switch customers should have specified other platings such as rhodium flash over another metal over the base contact metal. Also, the contacts of the sealed switch variety could be done with less metal-against-metal wear of the old, standard eyeletted or staked-together switches. That reduced long-term wear.
Nowadays the architecture of electronics has changed considerably. Radios that cover all of HF don't need rotary switches, their internal heterodyning methods obviate 'range switches.' Low-power bandswitches, if required by receivers, can be done with PIN diode electronics switches (FAR longer operating life). Lower-power contact relays are now abundant; see such as the Omron lines (plural) that are used in lower-power automotive applications. Automatic antenna tuners switch their banks of L and C by relays in a binary tree, coils driven by microprocessor control lines directly; coil powers are down to less than 100 mW. All of those applications cost less to make, drops the over-the-counter prices. A few old-style rotary switch parts are still available (once one finishes searching for one) but their piece prices are practically astronomical now.
OK, probably more than you wanted to know, but that is how it is. :-)
73, Len AF6AY
Reply to a comment by : K7PEH
on 2009-03-14So, why are these switches sealed like this?
Reply to a comment by : K1CJS on 2009-03-14
Nice tip! I may add that a wrap of electrical tape just may stand up better than scotch tape for 'plugging' the hole.