[Boatanchors] Audio matching xformer

[John Franke]

The wattages are given assuming a 70Vrms signal (actually 70.7Vrms).  Since 
the wattage is equal to the Vrms squared divided by the resistance, P = 
(70.7^2) / (600) = 8.33W, so use the common and ten watt terminals, which 
corresponds to 500 Ohms.
See: 
http://digitalcontentproducer.com/mag/avinstall_distributed_speaker_systems/

John  WA4WDL


----- Original Message ----- 
From: "Barrie Smith" <barrie at centric.net>
To: "Boatanchors Mail List" <boatanchors at mailman.qth.net>
Sent: Sunday, October 14, 2007 7:11 PM
Subject: [Boatanchors] Audio matching xformer


Hello, All:

I usually listen to my SX-73 using an old and tired Hallicrafters 600 ohm 
speaker, because 600 ohms is the audio output on that receiver.

I'd like to try a better quality speaker, but the speakers I have are all 8 
ohm.

I have a 70 volt, 10 watt line-transformer, but I can't make sense of the 
schematic.

The secondary is marked 4, 8 and 16 ohms, so that's FB.

The primary is marked in watts: Common, 10, 5, 2.5, 1.25 and .62 watts.

I would think that if this transformer could match 600 ohms to 8 ohms the 
primary would be marked in ohms.

I do not want to damage the receiver, so does anyone have an idea what's 
going on?

73,
Barrie, W7ALW, DN36au,
QRV 6M, 432 & 1296 EME
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