Monday, Sept. 5, 2016 — It has been a very busy couple of weeks here in the Zed Man’s humble shack … unfortunately, darn little of it involving Amateur Radio.
KEY CHANGES. I’ve still been active on CW, though less so due to other things keeping me out of the shack at net time. One of the biggest changes 
was that I decided to change out my 1937 McElroy Mac-Key and go back to my 100th Anniversary Vibroplex as my main key.
I love my 1937 Mac-Key, but I’m having a recurring problem with scratchy dahs — that’s right, the dits are fine, but the dah’s are giving me intermittent issues. I initially believed that the key was having electrical continuity problems between the pivot pin and the dah lever “bent lugs” that hold the lever in place. To eliminate that issue, I connected a small wire between a convenient ground point and the keying lever — similar in manner to the way Vibroplex insured electrical continuity in its bugs equipped with jeweled pivots.
But even with the added wire, I still ran into scratchy dahs, particularly if the dah lever moved vertically (there’s some play in the “lugs” that attach it to the pivot pin. I probably need to make sure the contacts are absolutely clean; there may be a continuity issue with my added ground wire. I’ll look into it, but for now running the 100th Anniversary key was my quickest way to avoid more embarrassment in a CW net situation when my dang dahs sound bad!
MON-KEYING AROUND. Despite my self-prescribed ban on eBay activities (outside browsing the site, of course), I have cast off my own declaration and jumped into the eBay pool o’ various and sundry Morse Code devices.
For weeks now I have been following an auction for a Mon-Key electronic keyer. The Mon-Key was one of the first commercial electronic keyers for the Amateur Radio market, and made its debut in the February 1948 issue of QST. I have picked up several Mon-Key keys over the years; none of them have worked — not necessarily due to their electronics, but due entirely to the use of a resistive line cord.
The Mon-Key did not use a power transformer to drop the line voltage. The filaments of the three tubes were in series with one side of the AC line — a 35W4 rectifier and two 12AU7, one of which was part of a multivibrator circuit, the second tube served as dual duty as relay control. But if you add the filament voltages, it comes to only 59 volts … it was up to the resistive line cord to convert the other 60 volts or so into heat. Makes you wonder how many users wondered if there was a problem with the unit when they realized the resistive line cord was running warm!
Resistive line cords were not that uncommon on inexpensive broadcast radios back in the time when higher voltage vacuum tubes did not yet exist in order to come up with a filament string of about 120 volts. It makes a power transformer unnecessary, which in the case of the Mon-Key, not only reduced its cost, but eliminated a large and heavy item that would have made the unit larger and heavier.
I have been meaning to get around to working on one of my Mon-Key keyers to replace the resistive line cord with either a power resistor or a non-polarized capacitor; the problem for either option may well be the available space. The Mon-Key is a pretty compact unit.
Anyway, after several weeks of seeing the Mon-Key listed with a reasonable Buy It Now price (and watching the seller slowly lower the price each week), I decided to take the plunge. At least I have something relatively rare now — the Mon-Key isn’t that common (but scarcity doesn’t equate to collectibility, of course), but this one works with the original line cord.
RESOURCES. The Nostalgia Air website has a couple of great articles on how to replace resistive line cords. An interesting video on YouTube also discusses replacing the resistive line cord with a non-polarized capacitor rather than using a power resistor. Yet another YouTuber has another take on the Mon-Key — he eliminated the resistive line cord, replaced the rectifier tube with diode rectifier, and the installed a small 6v transformer for the filaments.
EARLIER MON-KEY PURCHASE. I had to look up the best example of this key that I purchased eight years ago. This Mon-Key was in the original box with the manual, a flyer about the key, the original invoice and a letter to the buyer signed by the owner of the company. The buyer was a radioman in the U.S. Navy, and the Mon-Key had to be shipped air mail to his APO address.
The key doesn’t appear to have been in use for long, though perhaps it only saw gentle use because it is in absolutely in mint condition.
NYE MASTER KEY RE-REVISITED. While my opinion of the Nye Viking Master Key has only changed marginally since I put the key through its paces, I snapped one up on eBay over the weekend. Why a second Master Key when I’m not exactly a huge fan of this particular model? Capitalism son, pure capitalism! The key was listed for about half of the going Buy It Now price, and I don’t have a problem with a little speculative eBay buying and selling. In fact, I’m considering selling both of my Master Keys — or I’m going to figure out how to improve the feel of the key. I have read where some folks put a support under the base to keep the metal base from flexing, though I have yet to see if that makes a difference.
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