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Author Topic: Keyer for my Century 21  (Read 3248 times)
K4COP
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Posts: 22




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« on: October 11, 2014, 06:12:32 PM »

Looking for a Ten-Tec 670 keyer or similar that will work with my Century 21. Tha manual states that the keyer should be a reed relay type or have a positive voltage, or have a low saturation transmitter output circuit.   Can anyone tell me what other keyers would work with the Century 21?
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K5LXP
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« Reply #1 on: October 12, 2014, 07:05:54 AM »

I looked it up, and indeed they recommend a keyer output with a low saturation voltage.  The schematic for the TT670 keyer uses an MPS6514 NPN transistor, which has a .5V collector-emitter drop.  Looked up a 2N3904 for comparison, at the same base and collector currents the drop is .95V.   Because they specifically caution about this, one can only surmise they didn't buffer or otherwise accommodate key down voltage in the key circuit design.

Many keyers these days use output FETs, which can have a lower keying impedance than even the MPS6514 they recommend.  Alternatively you could modify any keyer you want to use an MPS6514 or a FET, or build an external interface that uses these or a reed relay (the relay would be the least preferred option).  Or better yet, modify the transceiver key input so that it doesn't matter what key or keyer you use with it.

Mark K5LXP
Albuquerque, NM
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K4COP
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Posts: 22




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« Reply #2 on: October 12, 2014, 03:39:34 PM »

Okay, thanks.  I am wondering of the MFJ Econo Keyer would worK.  I may just look for a single paddle key like a Vibroplex or Hi Mound.
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VA7CPC
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« Reply #3 on: October 12, 2014, 05:00:28 PM »

FWIW --

The K1EL Winkeyer USB uses "solid-state relays" for keying output.  Presumably, those are optimized for low voltage drop.

It's overkill for a hand-operated keyer, but it's quite nice as one.

.          Charles
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K8AI
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Posts: 69




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« Reply #4 on: October 12, 2014, 07:05:52 PM »

I use the MFJ Econokeyer with the Century 21. Works fine.

Curt
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K4COP
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Posts: 22




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« Reply #5 on: October 13, 2014, 11:07:08 AM »

Thanks for all of the input.  Since I am hoping to have a full HF rig soon, I will probably go with the Econo Keyer then.  The 21 is so easy to operate that I will be keeping it when I get the new rig.
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K4COP
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« Reply #6 on: October 13, 2014, 11:32:44 AM »

Curt:  Did you have to anything special for the keyer to work or did you just send it directly to the RCA key jack?
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KQ6Q
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Posts: 993




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« Reply #7 on: October 13, 2014, 05:30:39 PM »

I had a C-21, and before I got the 670 keyer, I was using a Heath HD-1410 keyer with it, which was compatible with tube rigs, and had diodes in series with the keyer output. I had to short out the diode to get it to work with the C-21. Details were in a Strays in QST back around 1980. Any current solid state keyer should be fine. When the C-21 came out, a lot of radios had tube finals, and keyers had to be able to cope with grid block keying and such. C-21 was a dandy radio - enjoy!

Fred, KQ6Q
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N4OI
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Posts: 214




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« Reply #8 on: October 14, 2014, 10:24:42 AM »

I installed the PicoKeyer Plus board from HamGadgets inside my C21 and it works great.   Wired power to the rig so no battery replacement concerns -- just set it up once and forgetaboutit!

73 ES GOD BLESS U ES URS DE KEN N4OI  Grin
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K4COP
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« Reply #9 on: October 15, 2014, 06:18:36 PM »

did not think about the Picokeyer Ken.  Thanks.  At what points did you tie in inside the radio?
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N4OI
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Posts: 214




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« Reply #10 on: October 16, 2014, 03:41:49 AM »

did not think about the Picokeyer Ken.  Thanks.  At what points did you tie in inside the radio?

Actually, the only support for the PicoKeyer board is the socket mounting through the back panel - I chose to drill a new hole.  It is so small and lightweight (without the battery), anything else is not needed -- unless perhaps for mobile use.  I just picked up the power internally somewhere (don't recall -- one of the buttons?) and re-routed the key line from the C21 socket to the PicoKeyer board.  (You could add a simple SPST switch if you want to be able to select keyer or straight key, of course.)   The sidetone is still from the C21.

I also have a PicoKeyer board (with battery) that I mounted in an Altoids tin that I connect between my paddle and other rigs that do not have internal keyers.  If you use the battery option, expect about nine months between replacements.  I have found the PicoKeyer very feature-rich and functional - with that comes a lot of cryptic setup procedures, but once it is done, it is done, even when replacing the battery. And the price is nominal.

I love my K3/P3, but still go back to the old C21 and OMNI D almost daily...  just pure CW fun!

73 ES GOD BLESS U ES URS DE KEN N4OI   Grin


 
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K8AI
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« Reply #11 on: October 19, 2014, 08:03:53 PM »

Curt:  Did you have to anything special for the keyer to work or did you just send it directly to the RCA key jack?

Just plug the C 21 into the Econokeyer's "direct" jack.
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AE5J
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Posts: 30




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« Reply #12 on: October 25, 2014, 07:44:33 AM »

Back in the day I used an MFJ Deluxe Memory Keyer and connected to the "direct" port. Worked fine. Today, I think I would agree that the Picokeyer would be the cleanest way to go. Easy to hook up, inexpensive and there is enough room inside the 21 for a small truck.
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