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 Post subject: Heathkit model a7 amp-
PostPosted: Apr Thu 08, 2010 6:08 pm 
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Location: Roseville,Ca
mornin' everybody!
i found an old amp in my '56's trunk this morning,marked model a7-how can i tell what letter version it is so i can put in the missing tubes and recap?
currently it has 1-12a6, a 12j5 and a 12sh7-3 others missing.
most likely it uses a 5y3 rectifier and another 12 a6.
any help appreciated,phil

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 Post subject:
PostPosted: Apr Thu 08, 2010 10:10 pm 
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Location: Utica, NY 13502 (USA)
According to this site, all of the A7 versions used the same tube line-up except the later versions added a 12SL7 phono preamp. (Note that two of your tubes are not on his list.)

http://www.kta-hifi.net/projects/amp_page/a7amp/a7.htm

You'll like this little amp.

Dave


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 Post subject:
PostPosted: Apr Thu 08, 2010 11:28 pm 
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Location: Roseville,Ca
thanks dave!
i figured the sockets were stuffed to fill the holes-now i have something to work with.
phil

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 Post subject:
PostPosted: Apr Thu 08, 2010 11:39 pm 
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Location: Rochester NY USA
A7B, C, D and E schematic on my web site: http://www.Aduiophile.cjb.net/Audio.html


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 Post subject:
PostPosted: Apr Fri 09, 2010 1:54 am 
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philco fan wrote:
thanks dave!
i figured the sockets were stuffed to fill the holes-now i have something to work with.
phil


Looks like you might have the "C" version and the website I pointed to is wrong about all having the same line-up.

Dave


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 Post subject:
PostPosted: Apr Fri 09, 2010 4:23 am 
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Location: Roseville,Ca
no worries dave-i checked the schematic and it didn't match so i figured it was a different letter model.
tom-i printed the "c" schematic and will check it against the amp,thanks for the info.
phil

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 Post subject:
PostPosted: Apr Sun 11, 2010 2:11 am 
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Joined: Jul Tue 18, 2006 5:23 am
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Location: Roseville,Ca
hi all,i have this little amp up and running.
after figuring out where the tubes went i put 2 shiney new jan/rca 12a6's in it and a shiney new jan/rca 5y3 rectifier and the other required tubes,some minor chassis work and then fed it with a 10 tube citation III f.m. receiver and out the amp to a 10 " philco[of course] pm speaker and it's thumping away,sounds pretty good for a little amp!
i'm probably gonna put it ebay in a week or so as i don't have any real interest in tube amps so i guess i'll see if anyone else does.
thanks to all that contributed.
phil

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 Post subject: Re: Heathkit model a7 amp-
PostPosted: Mar Wed 20, 2019 6:49 am 
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Joined: Jan Mon 25, 2010 7:51 am
Posts: 2716
Location: Toledo, Ohio
Here is reviving and old thread!

We just had our local Toledo Hamfest and I picked up one of these small Heathkit A7 amps as well. Interestingly enough mine looks to have the samd odd tube line up as you.

5Y3GT
12J5
12SH7
12SN7GT
12A6
12A6

I do have mine working...though needs a complete service. Did you end up finding a schematic for this version? There is some crude repair work in mine and I wanted to make sure of the component values.

Thanks!
Todd

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 Post subject: Re: Heathkit model a7 amp-
PostPosted: Mar Wed 20, 2019 2:13 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 5238
Location: Rochester NY USA
I have two of the same model (A7-C) in the queue. Now where did I put those 12SH7s? Schematic attached below. Bigger copy on my website (click my profile).

Attachment:
Heath_A-7C_800.gif
Heath_A-7C_800.gif [ 54.54 KiB | Viewed 945 times ]

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Last edited by Tom Bavis on Mar Wed 20, 2019 10:30 pm, edited 1 time in total.

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 Post subject: Re: Heathkit model a7 amp-
PostPosted: Mar Wed 20, 2019 4:06 pm 
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Joined: Jul Tue 18, 2006 5:23 am
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Location: Roseville,Ca
You know what?
I still have this amp,saw it out in the garage the other day,what a timely resurrection!

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 Post subject: Re: Heathkit model a7 amp-
PostPosted: Mar Wed 20, 2019 11:44 pm 
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Joined: Jan Mon 25, 2010 7:51 am
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Location: Toledo, Ohio
Thanks


T

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 Post subject: Re: Heathkit model a7 amp-
PostPosted: Mar Wed 20, 2019 11:56 pm 
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Location: Boston, MA USA
Todd, nice to hear from you!!

-David


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 Post subject: Re: Heathkit model a7 amp-
PostPosted: Mar Thu 21, 2019 12:34 am 
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Joined: Jan Mon 25, 2010 7:51 am
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Location: Toledo, Ohio
dberman51 wrote:
Todd, nice to hear from you!!

-David


Hi David! yeah I have not been on here much lately.

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 Post subject: Re:
PostPosted: Apr Wed 17, 2019 10:04 pm 
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Joined: Nov Fri 10, 2006 12:24 am
Posts: 2297
Location: Thornhill, Ontario, Canada
Dave Doughty wrote:
... You'll like this little amp... Dave
Right! Had one a while back... restored it... very good performance... sold it. You can't keep them all!
Cheers,
Roger

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Ontario Vintage Radio Assoc. http://www.ovra.ca


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 Post subject: Re: Heathkit model a7 amp-
PostPosted: Apr Fri 26, 2019 2:02 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 8735
Location: Beaver Falls, PA. USA
Heathkit got a lot of use from their stock of war surplus tubes. Besides the 12A6, you'll find 1619, 1625, 1626, and 1629 in various pieces of gear; they were all dirt cheap in those days.

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 Post subject: Re: Heathkit model a7 amp-
PostPosted: May Sat 04, 2019 9:30 pm 
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Joined: Apr Tue 17, 2012 7:58 pm
Posts: 109
Location: Metamora MI, 48455
They're nice little amps for what they are. Perfect for a small, cheap radio-phono setup. I know a ham who keeps one connected to a shortwave radio and a decent 12 inch full range speaker for SWL.


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