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 Post subject: matching transformer for 600 to 8 ohm AF output
PostPosted: Mar Mon 27, 2006 4:23 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 438
Location: far western end of Maryland...21561
Wondering what would work to match 8 watts at 600 ohm imp AF output to an eight ohm speaker. I normally use the little $2 PC board transformers for these matching tasks, but they are only rated to .4 watts so they are not going to do the job this time (on a Navy RBS receiver). I am not interested in replacing the original output transformer.<P>Any suggestions would be appreciated<P><BR>Thanks<P>Andy<P>------------------<BR>


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 Post subject: matching transformer for 600 to 8 ohm AF output
PostPosted: Mar Mon 27, 2006 4:36 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Morris Plains, N.J. 07950
Andy, I've been using the Hammond 600:8 matching transformers and they work very well. I've gotten good results on receivers such as an SX-28, SP-400 and SX-16. I think that both Radio Daze and Antique Electric Suppy carry these transformers and they're slightly less than $20 apiece. <P>Joe Connor<P>------------------<BR>


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 Post subject: matching transformer for 600 to 8 ohm AF output
PostPosted: Mar Mon 27, 2006 5:23 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 16281
Location: Utica, NY 13502 (USA)
In a pinch, I've used a 50L6 output transformer from a junker AA-5 chassis. Not an exact match by any means, but it seems to work.<P>Dave<P>------------------<BR>


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 Post subject: matching transformer for 600 to 8 ohm AF output
PostPosted: Mar Mon 27, 2006 5:29 pm 
Silent Key

Joined: Jan Thu 01, 1970 1:00 am
Posts: 34328
Location: Sandpoint, IDAHO 83864
Fair Radio Sales used to have lots of these for sale for around 5 bucks. However that was a few years ago. Might be worth a try checking them for one.<BR>Curt<P>------------------<BR>Curt, N7AH<BR>(Connoisseur of the cold 807)<BR>QCWA# 25085 AMI# 242<BR>CW forever


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 Post subject: matching transformer for 600 to 8 ohm AF output
PostPosted: Mar Mon 27, 2006 5:40 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1244
Location: Canyon Lake, TX
An ordinary filament transformer will work well. A transformer with a 120-volt primary and 12.6-volt secondary has a turns radio of 10 to 1 or an impedance ratio of 100 to 1. That will take 600 ohms down to 6 ohms. Six ohms will make a decent match to a 4 or 8-ohm speaker.<P>The standard fix is to use a 10-watt, 70-volt line transformer. They used to be available from Rat-Shack - I don't know if they still have them. The 10-watt tap provides a good match.<P>------------------<BR> <A HREF="http://www.gvtc.com/~edengel/TARC.htm" TARGET=_blank>http://www.gvtc.com/~edengel/TARC.htm</A>


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 Post subject: matching transformer for 600 to 8 ohm AF output
PostPosted: Mar Mon 27, 2006 5:52 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 840
Location: Whitman MA USA
I use a 70 volt line matching transformer, probably not the most effecient, but it sounds OK. I am planning to order one of the 600/8 ones from AES. Ross<P>------------------<BR>


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 Post subject: matching transformer for 600 to 8 ohm AF output
PostPosted: Mar Mon 27, 2006 9:59 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 262
Location: Eureka, CA, USA
Try HSC Electronics (halted.com). They have lots of odds and ends.<P>Jim Falls<BR>KG6FWT<BR>Eureka, CA<P>------------------<BR>


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 Post subject: matching transformer for 600 to 8 ohm AF output
PostPosted: Mar Mon 27, 2006 11:42 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 11912
Location: Warner Robins, GA
I also use the Hammond 600:8 matching transformer on my Hammarlund SP-600. It works very well. I mounted the transformer inside the wooden case that the speaker I'm using is mounted in (old jukebox speaker). No one would ever know that I'm not using a 600 Ohm speaker.<P>------------------<BR>


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 Post subject: Xformer
PostPosted: Apr Sun 23, 2006 5:55 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 314
Location: Denver, Co. USA
Try a doorbell or thermostat Xformer. 6, 12 or 24 V. Cheap at twice the price. George.


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 Post subject: Profile
PostPosted: Apr Sun 23, 2006 6:04 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 314
Location: Denver, Co. USA
Don't find contact for web-master. Need to correct "profile" info. George. gsmonroe2001@msn.com


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 Post subject:
PostPosted: Apr Mon 24, 2006 8:39 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2744
Location: Monterey California USA
A 70 volt line PA transformer, set to the correct tap, is quite close to 600 Ohms and works just fine, plus it costs under $ 5. This is not something where precision is important. You would have to be an audiophool to hear any difference between that and the Hammond transformer. You also have the advantage that the taps on the 70 volt transformer allow you to use it on other impedances to 5000 Ohms.

Unfortunately, Radio Shack has discontinued them as of 2004, however Alpex Electronics has plenty of Speco brand ones at less than $ 5 (look them up on Google) and local sound installers may be able to sell you one from a scrapped ceiling spaker assembly.


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