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 Post subject: AM Transmitter - - Any Good?
PostPosted: Jan Fri 05, 2018 2:25 am 
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Location: 44035 (Near Cleveland Ohio)
https://www.ebay.com/itm/AM-Transmitter ... SwMvtZOei1


Ran across this unit - was wondering if anyone had an opinion. I procrastinated buying a SSTRAN for so long, that they couldn't wait for my order and went out of business . . . :D


Dan


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 Post subject: Re: AM Transmitter - - Any Good?
PostPosted: Jan Fri 05, 2018 3:44 am 
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Location: Saskatoon
I can't say anything about signal quality, because I've never heard one. However, based on the Ebay info we can get some general ideas.

Looking at the parts:
1. MC145151 PLL frequency synthesizer chip to generate the carrier frequency. So, it should provide a stable frequency. Unfortunately, this chip is now obsolete, so there's no telling how long these kits will remain available.
2. CD4017 decade counter. This is used in conjunction with the PLL chip to step the frequency up or down.
3. TDA7284 an audio auto level control circuit. So it shows that the circuit can compensate for program material having different volume levels. A good sign. Unfortunately, it looks as if this part may also be obsolete, or close to it.
4. Modulation appears to be done with the discrete transistors. No way to trace the circuit based on the photos. So, can't make any comment on that.
5. There is circuitry included for antenna matching. Another good sign. I've seen a bunch of simple transmitters that don't have this, and consequently they can't get any decent range.

One thing that I find surprising is that you don't get a proper printed circuit board, just a piece of perf board, and then you have to wire all of your components point to point. This is really the only drawback that I can see. Maybe this was done in order to avoid having to get FCC approval.

For what you get, the price looks reasonable.


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 Post subject: Re: AM Transmitter - - Any Good?
PostPosted: Feb Thu 01, 2018 4:21 am 
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Location: Plymouth, MI
I've wasted money on cheap am transmitters before I tried this tube transmitter. Hands down the best! I bought a second one because I don't know how much longer the builder will be making them.

Attachment:
AM Tube Transmitter-e.jpg
AM Tube Transmitter-e.jpg [ 228.77 KiB | Viewed 578 times ]


Not cheap, but not cheap transmitter results either!

He sells them on EBay!

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Last edited by atwaterkent1 on Feb Fri 02, 2018 3:54 am, edited 1 time in total.

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 Post subject: Re: AM Transmitter - - Any Good?
PostPosted: Feb Thu 01, 2018 4:45 pm 
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Location: Albion, CA, USA
atwaterkent1 wrote:
I've wasted money cheap am transmitters before I tried this tube transmitter. Hands down the best! I bought a second one because I don't know how much longer the builder will be making them.
Not cheap, but not cheap transmitter results either!

He sells them on EBay!


I can't seem to find it on ebay. Any more details or a link?

Thanks!


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 Post subject: Re: AM Transmitter - - Any Good?
PostPosted: Feb Fri 02, 2018 1:47 am 
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I typed in AM Transmitter and it was the second auction listed.

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 Post subject: Re: AM Transmitter - - Any Good?
PostPosted: Feb Fri 02, 2018 1:49 am 
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Heres the link:

www.ebay.com/itm/AM-BROADCASTER-TRANSMI ... Swf~9Za1YP

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 Post subject: Re: AM Transmitter - - Any Good?
PostPosted: Feb Fri 02, 2018 2:51 am 
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Location: Saskatoon
I remember that transmitter being mentioned in another thread here on the forum. At the time, out of curiosity I traced the circuit from the photo of the underside. There wasn't anything in particular that stood out as especially novel, but how well it works is all in the details, of course.


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 Post subject: Re: AM Transmitter - - Any Good?
PostPosted: Feb Fri 02, 2018 2:53 am 
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Sorry for not finding it but thanks for the link! Pretty expensive but I am seriously considering it. Since you have one, do you think it would be fairly easy to put it in a nicer looking case?


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 Post subject: Re: AM Transmitter - - Any Good?
PostPosted: Feb Fri 02, 2018 3:32 am 
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You should have no problem with doing that.

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 Post subject: Re: AM Transmitter - - Any Good?
PostPosted: Feb Fri 02, 2018 5:17 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Saskatoon
I found the link where we previously discussed this.
viewtopic.php?f=12&t=317228

I realize that the Ebay seller is never going to get rich selling these things. So, I'm not going to criticize his price. But even so, for way less money, you could build Norm's 6888 transmitter or one of its variations, and get an excellent transmitter.


Last edited by BobWeaver on Feb Fri 02, 2018 11:24 am, edited 1 time in total.

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 Post subject: Re: AM Transmitter - - Any Good?
PostPosted: Feb Fri 02, 2018 5:27 am 
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Why spend almost three hundred with shipping on this?
In the Home Brew forum we have seasoned members using modified two dollar LM 386 amplifier boards that are purported to be excellent transmitters.

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 Post subject: Re: AM Transmitter - - Any Good?
PostPosted: Feb Fri 02, 2018 10:10 pm 
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I can only comment on the transmitters I've tried. Yes, it's pricey, but it's so good and clear, no drift. By the way, the seller is a great guy and has around 50 years of experience in broadcasting, I know of no one who has that much experience with transmitters. I spoke to him for over an hour when I ordered the second unit and he was very pleasant.

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