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 Post subject: Part 15 AM transmitter hum reduction
PostPosted: Mar Thu 01, 2018 4:21 pm 
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Location: Warner Robins, GA
Does your part 15 AM transmitter hum?

Do you want a solution that effectively reduces hum?

All you need to do are these two things.

1. Install an Edcor WSM15K/15K balanced/unbalanced to balanced/unbalanced audio transformer.

https://www.edcorusa.com/wsm_series

If building a transmitter or there is room in an existing transmitter install the transformer inside the case for the transmitter.

Can be added to an existing transmitter where there's no room in the case by installing in a box and using as short of a cable as possible between the box and transmitter.

What that does is

1. Isolates the transmitter's circuit ground from the input ground
2. Ensures the only ground is the transmitter's ground which ensures there's no ground loop
3. Eliminates the effect on the transmitter from
..A. The audio cable
..B. The source
..C. The source's power supply cable
..D. The source's power supply
..E. Anything else plugged into the source if the source is for instance an output jack on your stereo system or computer




2. Install a ground lift switch

Some radios hum less with the transmitter ground connected.
Some radios hum less with the transmitter ground disconnected.

I have yet to test a transmitter grounded directly to a ground rod. Perhaps that would reduce hum even more or make it to where the ground can be permanently connected.


Last edited by Tube Radio on Mar Fri 02, 2018 5:01 am, edited 1 time in total.

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 Post subject: Re: Part 15 AM transmitetr hum reduction
PostPosted: Mar Thu 01, 2018 8:20 pm 
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Location: Mission Viejo, southern California
Thanks, I will try that.

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 Post subject: Re: Part 15 AM transmitetr hum reduction
PostPosted: Mar Fri 02, 2018 12:13 am 
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You're welcome.


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 Post subject: Re: Part 15 AM transmitetr hum reduction
PostPosted: Mar Fri 02, 2018 1:02 am 
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My SSTrans wasn't giving me the cleanest of signal reception, but after reading some of the information on the board, I relocated it so that it's vertical antenna lead went up against a section of wall that had no electrical cable inside. The difference was like night and day.

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 Post subject: Re: Part 15 AM transmitter hum reduction
PostPosted: Mar Fri 02, 2018 5:02 am 
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That can greatly affect the transmitter as well.


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 Post subject: Re: Part 15 AM transmitter hum reduction
PostPosted: Jul Fri 06, 2018 3:13 am 
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Location: Plymouth, MI
I don't have any signal problems using this transmitter.

Attachment:
AM TRANS.jpg
AM TRANS.jpg [ 6.94 KiB | Viewed 901 times ]

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 Post subject: Re: Part 15 AM transmitter hum reduction
PostPosted: Jul Fri 06, 2018 4:31 am 
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atwaterkent1 wrote:
I don't have any signal problems using this transmitter.

Attachment:
AM TRANS.jpg
I bought one of those to try and will report on how it performs for me.

Finding a place in the house with no wires or pipes in the wall which is also a reasonable place for a transmitter is not as easy as it sounds.

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 Post subject: Re: Part 15 AM transmitter hum reduction
PostPosted: Jul Fri 06, 2018 4:42 am 
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I don't believe that you have to worry about plumbing pipes, Stephen; it's the AC lines that cause the havoc.

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 Post subject: Re: Part 15 AM transmitter hum reduction
PostPosted: Oct Mon 01, 2018 5:31 pm 
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Location: Beaver Falls, PA. USA
The commercial audio field used transformer coupling for many years. The Edcor transformers are inexpensive, which is good; the "classic" transformers from the old days bring $$ on the bay.

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 Post subject: Re: Part 15 AM transmitter hum reduction
PostPosted: Oct Mon 01, 2018 6:08 pm 
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Location: Warner Robins, GA
Tim Tress wrote:
The commercial audio field used transformer coupling for many years. The Edcor transformers are inexpensive, which is good; the "classic" transformers from the old days bring $$ on the bay.


Plus Edcor will pretty much make most any transformer you need, although you pay a one time design fee after which anyone can buy that transformer for its normal cost.


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