[R-390] Speaker 600

[fev]

Hi Chuck,
In Antique Electronic Suply http://www.tubesandmore.com/  you can buy
one for 16.50 dollars , here is the description:

TRANSFORMER, AUDIO INTERSTAGE, HAMMOND, 12 WATT 

Developed in response to requests from the "Collins Collectors
Association" , this is a matching audio transformer for older equipment
with 600 ohm audio output, driving modern speakers. 

Or for "classic" high impedance speakers used with newer equipment,
simply swap primary for secondary (ie...4 or 8 ohm input and 600 ohms
out). 

Key Features Isolation unit: (i.e. seperate primary and secondary)
Primary: 600 Ohm (with 6" wire leads)
Secondary: 8 Ohm with 4 Ohm center tap (with solder lugs) 
Power: Rated at 12 watts
Frequency Response: 30 Hz - 20 kHz
Weight: 1.3 lbs.
Mounting: 2 hole u-bracket mount - on 2-3/16" mounting centers

Regards,
Francisco LU3eec

-----Mensaje original-----
De: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
En nombre de Bob Camp
Enviado el: Miércoles, 22 de Septiembre de 2004 10:39 p.m.
Para: Charles B; R-390 HF Receiver List
Asunto: Re: [R-390] Speaker 600


Hi

It's been a *long* time since I have seen a normal sized speaker with a 
600 ohm impedance.

What is normally done is to get a 600 ohm to 8 ohm (or 4 ohm) 
transformer and use a normal speaker. The transformers are available 
from a variety of sources ranging from eBay to Digikey to Radio Shack. 
Typically ones that are big enough to do the job run in the $10 to $20 
range.

Another option is to get one of the military speakers. The ones you 
want have an 8 ohm speaker and a transformer built into the enclosure. 
Some of these can be a little expensive but they often look neat teamed 
up with an R-390.

To get a "true" 600 ohm speaker I would look into the horn speakers you 
commonly see used in stadiums. The horns and drivers are generally sold 
separately. Drivers are available in a variety of impedances including 
600 ohms. I'd have to admit that 600 ohms is not exactly the most 
common driver to find lying around ...

The final option is to pick the audio off the radio at the diode load 
test point and drive it into a high impedance input on a audio 
amplifier. This takes the whole audio section of the R390 out of the 
act. A lot of audio amplifiers will work. A good old tube based mono 
amplifier is often used.

	Take Care!

		Bob



On Sep 22, 2004, at 4:39 PM, Charles B wrote:

> Hi all,
>
> Where can I find a 600 ohm speaker or where can purchase one?
>
> Is it possible to convert an 8 ohm speaker to 600 ohms?
>
> Thanks
>
> Chuck
>
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