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RE: Radio for Radio
To: CRTech <crtech@crtech.org>
Subject: RE: Radio for Radio
From: Mike Price <mprice@srnradio.com>
Date: Tue, 11 Sep 2018 15:14:41 +0000
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Thread-topic: Radio for Radio

A regular 600:600 transformer will do nicely.  Even a small one will do as transformers love to be driven by low impedances.  Years ago, the company I worked for used communications grade transformers  (300 to 5000 Hz.) for our console outputs.  We were able to get 20 – 25,000 Hz with very decent distortion because the transformer was being driven by a 25 ohm source impedance. Don’t forget the 8 ohm load resistor on the output of your car radio to keep it happy.  It doesn’t have to be very large as the radio will run at less than 1/5 watt for +4dBu. out of the transformer.



Michael W. Price

Digital Product Engineer

Salem Radio Network

6400 Belt Line Rd., STE 210

Irving, TX  75063






From: Mark Carol Bohnett [mailto:mbohnett43@bevcomm.net]
Sent: Monday, September 10, 2018 2:30 PM
To: CRTech
Subject: Radio for Radio


Dear Sirs


We have a Full Power site in Minnesota that is fed primarily with a IP based signal.  The emergency back up has been an off-air broadcast receiver but the antenna is only 15ft off the ground, directly in behind a large self supporting tower (lots of grounded steel).  Depending on the day, the signal is fair but never clean.  In fact I have to point my antenna between the steal struts to get any signal. 


If I move the antenna and pole to the other side of the tower, the signal and sound quality is perfect.  The problem is the site is owned by American Tower who charges you for the very air you breath while on site!  We are attempting not to add more monthly costs to a moderately supported signal; therefore, we are searching for an alternative.


I was commissioned to use a "car radio" for a test (and to my surprise) and the audio quality was actually better that the professional receiver. 


Now I have to build a site with a car radio and interface it into the broadcast world.  I have used in the past the Bogen impedance matching transformers.  The spec is 10K input to 600 balanced out.  The speaker output of the radio is 8 ohmn therefore, I am looking for a 8 ohmn to 600 ohmn transformer.  I found the "Classic 119DA" transformer but they are pretty pricey.  Has anyone found (in this same or like situation) some "miracle" cure for matching a car radio into a line level device (preferably without a amplifier in between)?


If not, I'll probably go with the Bogens and hope for the best, but I wanted to see if any one had found a better alternative before I build the site.


Any thoughts would be appreciated.


E. Mark (MN)

References: Radio for Radio
(Mark Carol Bohnett <mbohnett43@bevcomm.net>, 10 Sep 2018 19:29:59 -0000)
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