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 Post subject: Sparton Equasonne
PostPosted: May Tue 21, 2019 11:13 pm 
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Joined: May Tue 21, 2019 11:08 pm
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Hello all, I am restoring a 600 Sparton radio and am in need of two 483 tubes. Is there a substitute for these tubes?
Thanks
Larry


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 Post subject: Re: Sparton Equasonne
PostPosted: May Wed 22, 2019 1:39 am 
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Location: Dayton Ohio
Hello and welcome to the Antique Radio Forums. :D

Well, the best thing is to find two 483 tubes, but a pair of 71A tubes will work in a pinch. They will be run hard and may not hold up if used alot, but will work for a while.

Also the 485 tubes in the RF amplifier box. Make sure there aren't any 27 tubes in there. They pull way more current and will stress out the power transformer.
If a sub is needed, try a 56 instead.

-Steve

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Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


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 Post subject: Re: Sparton Equasonne
PostPosted: May Wed 22, 2019 2:07 am 
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Ok Thanks for the reply, I'm good with 485s just not 483
Thanks again
Larry


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 Post subject: Re: Sparton Equasonne
PostPosted: May Wed 22, 2019 7:03 pm 
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Agree 71A will work. There is also a 482 that will operate. Whatever you decide use the same number tube is both sockets.

When I tried 56's for 485's gain was too much and the amplifier oscillated. There is a 484 that will work here. To eliminate distortion may need to move around 485 tubes?

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 Post subject: Re: Sparton Equasonne
PostPosted: May Wed 22, 2019 7:14 pm 
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Location: Dayton Ohio
Sparton has a procedure to install the 484/485 tubes. I'll see if I can scan it.

My first Equasonne was a model 750 which had the power transformer replaced with one from a Philco sometime in its life. One big massive transformer! I'm not sure what Philco it came out of.
As the heater winding is 6.3V, they replaced all of the 485s with 76s. (which are comparable in characteristics to 56s)
I had to undo the work they did on the power chassis as it had 42s in the output and a 5U4G installed.

I put a pair of 81s and 50s back in with the 50s wired to the 6.3V winding and the two 81s on the 5volt winding.
Surprisingly, the radio works great! I know the 50s are underpowered, and the 81s even more so, but that radio was what got me hooked on Sparton!
It has amazing performance considering I was taken aback at the design. When i first saw the schematic, I couldn't believe such a contraption would work.

It made a believer out of me :D

I do have what i need to make it right now, but I almost hate to mess with it.

-Steve

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Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


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 Post subject: Re: Sparton Equasonne
PostPosted: May Thu 23, 2019 2:06 am 
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Location: Under the Blue skys of OR 97524
I ran a couple of 45s in series on a 410 until I got some 183 globes and it worked well. I think that I had to disconnect or rewire the hum-pot.

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http://russoldradios.com/


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 Post subject: Re: Sparton Equasonne
PostPosted: May Thu 23, 2019 11:43 am 
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Russ, that is a great idea! I hadn't thought of that. :D

Yes, a little rewiring, but 45s are a better match.

-Steve

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


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 Post subject: Re: Sparton Equasonne
PostPosted: May Fri 24, 2019 10:14 pm 
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Joined: May Tue 21, 2019 11:08 pm
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Thanks all for the replies. I am very new at this, and have another question. In the Sparton RF amp box there are metal tubes next to the 485 tubes. Are they just condensers or a combo part.
Thanks again
Larry


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 Post subject: Re: Sparton Equasonne
PostPosted: May Fri 24, 2019 10:42 pm 
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Location: Under the Blue skys of OR 97524
As I recall, they are capacitors.

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"I just might turn into smoke, but I feel fine"
http://russoldradios.com/


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 Post subject: Re: Sparton Equasonne
PostPosted: May Sat 25, 2019 1:59 am 
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phlogiston
Thank you, I cut them out and replaced. I was hoping they didnt have coils in them also


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 Post subject: Re: Sparton Equasonne
PostPosted: May Sat 25, 2019 3:42 am 
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Joined: Dec Thu 31, 2009 4:28 pm
Posts: 4751
Location: Under the Blue skys of OR 97524
All I can really remember about them is that they were kind of hard to rebuild (re-stuff) because of the post that runs through them.

I have done quite a few of those sets and it seems that each one has a different personality when it comes to tuning. Some tune just like a TRF and some seem to drag the stations around the dial a little. Moving tubes around can make a difference - Strong - Weak(er) - Strang - Weak(er), is what is supposed to work best.

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"I just might turn into smoke, but I feel fine"
http://russoldradios.com/


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