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 Post subject: E.H. Scott 16A Power Amp chassis- operation without tuner?
PostPosted: Apr Sat 13, 2019 6:28 am 
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Curious if the 1948 E.H. Scott 16A Metropolitan amplifier chassis can be run by itself without the separate chassis tuner preamp plugged in?
Seems to me the power transformer may get taxed without a resistor added or something to the jack, without all those tubes being powered
on the tuner/preamp chassis I don't have to plug in.

I know from experience that the H.H. Scott (not related) 220-A laboratory amplifier requires a resistor plug instead of 120 preamp or the power transformer will fry.

I've been looking at the Riders and the photofact for this 16A amplifier and am not quite sure if I can run this as a solitary unit, I have Jones plugs
and compatible speakers,etc


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 Post subject: Re: E.H. Scott 16A Power Amp chassis- operation without tune
PostPosted: Apr Sat 13, 2019 11:17 pm 
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https://picclick.com/EH-Scott-16A-Metro ... id=1&pid=1

It will need some rewiring as a preamp to use it as a stand alone amp

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 Post subject: Re: E.H. Scott 16A Power Amp chassis- operation without tune
PostPosted: Apr Sat 27, 2019 11:22 pm 
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FYI - Scott Radio Labs is the post war successor to E H Scott Radio Labs of 1930's fame. The 16A is an 800-B with many features deleted.
The model 16A amp/power supply comments:
1) The FM's IF circuit for the this radio resides on the amp chassis. I suppose you will bridge this circuit, or at least remove those tubes.
2) Note the 16A diagram has a carry over from the early 800-B Scott - backwards speaker compatibility - a 750 ohm power resister mounted on the speaker in place of a field coil of the early production 800-B B+ runs to/through the speaker plug socket for that outboard power resistor. .

Assuming you also disconnect the FM section, that doesn't leave much load for a really beefy power supply sized for the 28 tube radio.
Be interested in how you make out.

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 Post subject: Re: E.H. Scott 16A Power Amp chassis- operation without tune
PostPosted: Apr Sun 28, 2019 12:09 am 
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Thanks Dave for your insights!
I haven't decided yet whether to use the existing output transformer for a similar era Thordarson compressor amp build (Still have to find correct power transformer for those plans) and part the rest out, or just look for a affordable 16a tuner section to run with the main amp and restore it eventually...
I don't think it would be wise to run a power transformer that large without a appropriate load for any estimable length of time.


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 Post subject: Re: E.H. Scott 16A Power Amp chassis- operation without tune
PostPosted: Apr Sun 28, 2019 3:10 am 
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Consider : if you have the 16A receiver to restore (or seek one to restore), you would have a high quality radio with plenty of audio power. Any 8 ohm speaker or 8 ohm speaker system would suffice, as long as you somehow added the outboard power resistor needed in the B+ circuit. I have restored an 800-B and it is an audio power house. The 16A has nearly the same audio circuit, just without, all the relays, pushbutton tuning and Short Wave. Has a magic eye tuning indicator.
The FM circuit is high quality (and AM is good too, if you have any decent AM stations available). Consider the phono input as an AUX input. The 16A receiver has bass and treble controls.
The Scott Radio Lab model 16A receiver has an interesting feature - the Scott Labs 800-B did not have: the H. H. Scott Dynamic Noise Suppressor - a 4 tube record scratch suppressor and low frequency rumble and hum suppressor that preceeded when H H Scott's own retail version 112-A Dynaural Noise Suppressor.of 1948. (Look it up). The model 112-A (and 3 tube 111_A) were H H Scott's first retail hi fi product and by the mid 1950's, H H Scott products lead the way in component Hi-Fi home audio.
Note- the AC line goes through the speaker plug and to the receiver then back to the primary of the power transformer. This was a safeguard against risk of powering up the amp alone.

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 Post subject: Re: E.H. Scott 16A Power Amp chassis- operation without tune
PostPosted: May Fri 10, 2019 8:03 pm 
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ampstamp88 wrote:
... I don't think it would be wise to run a power transformer that large without a appropriate load for any estimable length of time.
Running any size of power transformer without a load will not harm it. Reason: it will only pull a small magnetizing current... power dissipation will only be iron losses, very low. However, with a reduced load the downstream voltages might be a bit higher and may need adjustment.
Cheers,
Roger

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 Post subject: Re: E.H. Scott 16A Power Amp chassis- operation without tune
PostPosted: May Wed 22, 2019 3:28 pm 
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You might be interested in this project:

https://www.russoldradios.com/blog/scott-mp3-adaptor

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 Post subject: Re: E.H. Scott 16A Power Amp chassis- operation without tune
PostPosted: May Wed 22, 2019 6:16 pm 
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Thank you Russ and Roger for your posts, quite helpful in deciding how to approach this 16A.
I was going to use the output transformer off the 16A for another project, but now I think
I'll leave it alone until I have some time to devote to the 16A with this information.
-Kent


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 Post subject: Re: E.H. Scott 16A Power Amp chassis- operation without tune
PostPosted: Jun Thu 06, 2019 2:52 pm 
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Search for a proper tuner chassis or maybe you could find a later AM/FM tuner that can be powered by the Scott power supply.


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 Post subject: Re: E.H. Scott 16A Power Amp chassis- operation without tune
PostPosted: Jun Thu 06, 2019 7:27 pm 
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I have restored 3 800B Scotts. I now have a 16A. I might miss the power tuning but it certainly is as good a receiver and amp as the 800 with a lot of stuff for the record player that I don't use. The 800 and 16 are really not appreciated as great receivers and amps. They were just "born to late" for most collectors. My 16 picks up AM and FM with good antennas. Mostly I run it though an aux input to an Amazon Alexa Dot which has an audio output. I can get all the music I wish seek just asking her!
In a custom made cabinet by a good friend it is quite "compact".

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 Post subject: Re: E.H. Scott 16A Power Amp chassis- operation without tune
PostPosted: Jun Fri 07, 2019 12:35 pm 
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Another thing I thought of. You could do two separate chassis. One for AM/SW such as something from an old console radio or better table radio where the cabinet is too far gone and a Browning or similar FM tuner.


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