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 Post subject: Ohmite D-101?
PostPosted: Mar Mon 18, 2019 3:22 am 
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Joined: Jul Sat 28, 2012 9:32 pm
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I've run up on an Ohmite D-101 100 watt dummy antenna 600 ohms, because I need something to work on my Knightkit T-60 transmitter. But if the dummy load is 600 ohms, what good is it? For what purpose would a 600 ohm dummy antenna be made?


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 Post subject: Re: Ohmite D-101?
PostPosted: Mar Mon 18, 2019 4:01 am 
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Location: Roanoke, VA
How old does it appear to be? In the 1930s 600 ohm open-air transmission lines were pretty common for radio amateurs, so they could use a 600 ohm dummy for transmitter tune-up and testing.

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 Post subject: Re: Ohmite D-101?
PostPosted: Mar Mon 18, 2019 4:27 am 
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Thanks. You answered my question and it's all I need to know. I can't use it. It's on ebay right now for 4 or 5 dollars.


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 Post subject: Re: Ohmite D-101?
PostPosted: Mar Mon 18, 2019 6:50 am 
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Is it in a can?

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 Post subject: Re: Ohmite D-101?
PostPosted: Mar Mon 18, 2019 8:25 am 
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henry finley wrote:
For what purpose would a 600 ohm dummy antenna be made?
600 ohms is standard impedance for audio systems.

Your item is a dummy load, but not a dummy "antenna".

- Leigh

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 Post subject: Re: Ohmite D-101?
PostPosted: Mar Mon 18, 2019 9:09 am 
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Location: Cedar Rapids, Iowa, USA
I have found pictures of D-100 clearly marked DUMMY ANTENNA RESISTOR at 73 and 146 ohms. I have not seen one for 600 ohms.


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 Post subject: Re: Ohmite D-101?
PostPosted: Mar Mon 18, 2019 1:26 pm 
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 Post subject: Re: Ohmite D-101?
PostPosted: Mar Mon 18, 2019 2:21 pm 
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Leigh wrote:
henry finley wrote:
F600 ohms is standard impedance for audio systems.

Your item is a dummy load, but not a dummy "antenna".

Leigh - After almost 50 years of working with 600 ohm audio lines I have never seen one that would need a 100 watt dummy. Whether they be studio audio lines or telephone lines their power is measured in milliwatts, unlike 70 volt or 100 volt speaker lines. I would note also, after nearly 50 years of working in broadcasting, that a number of transmission line standards were used in the decades preceding the development of coaxial lines.

Dale H. Cook, Radio Contract Engineer, Roanoke/Lynchburg, VA

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