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Title: reed relays for keying an old Globe Chief Model 90 Post by: KK4RF on August 21, 2011, 06:58:33 AM Gentlemen:
I'm trying to get my Dad's old Globe Chief Model 90 back on the air. It keys fine with a straight key but my various electronic keyers won't work with it. It uses "modified grid-block keying." My keyers work fine with other transmitters using grid-block keying. I've made keying adapters in the past using a high voltage keying transistor that will handle negative voltages. The Chief has a negative 67 volts across the key line. My adapter won't work. I've decided to try a reed relay. Does anyone have a recommendation for a reed relay that will handle the voltage present here? I'd like to get a brand name and model number of something that I could order from Mouser or Digikey or any ideas would be welcome. I'd still like to figure out a way to key the Chief with a tranistor if anybody has an idea there. My Dad, W8ZLC, became a Silent Key last year and since then I've been trying to get his old rigs back on the air. The Globe Chief would be fun to use, but I can't operate a straight key worth a darn. I need to use a keyer somehow. Thanks. ---Marty, KK4RF--- Title: Re: reed relays for keying an old Globe Chief Model 90 Post by: KK4RF on September 03, 2011, 08:23:58 PM Gentlemen:
Thanks to all who read my original post a couple of weeks back. I wasn't sure a reed relay would work in this situation as I estimated there must be about 200 mA of current to be keyed and there is a minus 65 volts across the contacts. I found an old reed relay in the junk box and made a keying circuit with a keying transistor and a driver transistor for the relay itself. The keying transistor between the keyer and the driver transistor. Anyway, it keys the old Globe Chief just fine. Another ham on the HW-16 website suggested the Jackson Harbor Press Keyall adapter, which I ordered on-line. It's a neat little circuit that will key up to 500 volts, of either polarity, and up to 2.5 amps. Only 14 bucks. Just got done putting it together. It keys the old rig just fine also. Anyway, I just wanted to post that there at least 2 ways to key this old transmitter and using my electronic keyer to do it. Fun project overall. ---Marty, KK4RF--- Title: Re: reed relays for keying an old Globe Chief Model 90 Post by: KM1H on September 07, 2011, 06:23:48 PM Ive seen reed relays in commercial amps that can handle 1200W but not hot switched, a perfect sequencer is needed for QSK. Kenwood used little ones in some older transceivers....maybe they still do.
OTOH my Kansas City Keyers have handled any rig I put them on including a few Globes. I tossed the straight key at the same time I got rid of crystal control in 1956. My folks gave me a Vibroplex Presentation for my 16th birthday. Carl Title: Re: reed relays for keying an old Globe Chief Model 90 Post by: KK4RF on September 08, 2011, 02:01:02 PM Carl, AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Thanks for the info on the high power reed relays. Not sure how much voltage and current mine can handle but it keys the old Globe Chief very nicely. I hadn't heard of the Kansas City Keyer before but I looked it up on the internet and appears to be a very nice looking unit. Thanks again. ---Marty, KK4RF--- |