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McKay-Dymek Tuners and antennas

K

kenglish

Guest
I told the KSL-AM CE that, one day when I had a few minutes at lunch, I'd clean up the old McKay-Dymek AM-5 Tuner that's been sitting in a rack upstairs. Today was the day.

While I let it warm up, thought I'd ask:
Anybody still got one in use? Any of the old Dymek stuff still kicking around?

I have an old DA-9 antenna at home (needs some switch and pot cleaning, but works), and a DA-100 antenna from the last stock at Universal Radio.
 
I have an AM-5 and the companion loop antenna, and use it from time to time.

I did change the lighting of the dial to LED.

It's a fantastic receiver, albeit not a DX machine, especially when there is a close by IBAC station.
 
I looked a bit closer last night...I found I actually own the DA-5, not the DA-9.
I got the original stuff in 1984, when the local electronics wholesaler put the Dymek's on their clearance table, cleaning out stuff they forgot they had in the warehouse. I bought the DA-5 and a couple of DA-100D. They didn't have an AM-5, but they did have a couple of the 33's (super-nice shortwave units), that I think sold for about $3K retail. Seems like they wanted about $600 each, but I couldn't afford one :'( .

Has anybody ever seen schematics for the McKay-Dymek line?
 
So far, I've changed out the lamps (except the "grain-of-wheat" lamp on the dial pointer), and am repainting the covers (they had bad gouges from an amp that sat on top years ago in the Promotions guy's office).
It sounds OK on a small test speaker, but has no low-end on the big ones, so I'll re-cap the audio circuits.
 
Trying to figure out what the tiny light bulb in the dial pointer is. It was held in with just a dab of model-airplane cement, so it came out intact.

Look like about nine electrolytic caps to swap out. Think I'll go with exact replacements, then maybe try some of those exotic audiophile ones later ;) .

I'm already thinking about how I'd design the latest generation of one of these.
 
kenglish said:
Trying to figure out what the tiny light bulb in the dial pointer is. It was held in with just a dab of model-airplane cement, so it came out intact.
Click to expand...

It is probably a "grain of wheat" lamp, which is fairly common in model railroading circles. Try your local hobby shop.
 
Looks like it is a C-M 6838, 28 Volts with wire leads.
Spent a lunch hour looking for caps. Nothing in the Vishay line matches exactly. Guess I'll try some of the others (Vishay was all they showed on one catalog's site.)
 
Ordered nine caps and a box of bulbs from Allied a few days ago. They came yesterday, and I swapped out the old parts. Seems to have some really good low end now.
Wondering....when I turn the desk lamp (fluorescent) on or off, right next to it, with the covers off the tuner, AGC seems to lock up, and audio drops way down. I'll have to try it with the covers back on.
 
Set it up on the home balcony the other night, with the DA-5 antenna I already have. Used a headphone amp and some good headphones.

Seems that the audio level pot still needs a little cleaning, and the dial isn't tracking real well at the lower end of the scale. Otherwise, it's amazing how good AM Radio can sound. Local oldies station KDYL sounds good-to-great, depending on the source. Country KSOP sounds every bit as good as a clean FM. Listened to Sporting News Radio (out of Houston) on local station Zone 1280, and could hear every squeak of the host's chair back and the wheels, as well as people talking in the hallway outside the studio.....Hey! This is "A-M radio".

As far as DX'ing, the combo worked pretty well for the 50KW guys out of Denver and Window Rock. And, even KMTI (Manti, Utah) came in very listenable, with some "white noise". The McKay-Dymek DA-5 antenna outperformed the Ramsey Signal magnet antenna, which has a ferrite bar a bit shorter than the DA-5's 12-inch one. The Ramsey was best when the bar was vertical, nulling out most local electrical noise.

It got late, so I didn't try the 50-foot longwire, or the omni DA-100D.
 
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