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Now here's a serious tuner!

66.74.72.231

Posted by Bambi B on August 16, 2004 at 20:12:34

Mates,

I think all audio equipment should looks like this!

http://www.fmtunerinfo.com/Harvey193r-m47.jpg

Description of this Harvey Radio Labs:

http://www.fmtunerinfo.com/audioghosts.html

"Harvey Radio Labs 193R model 47 (1947, front, inside) - Harvey Radio Labs was similar to REL. This monster 17-tube, dual conversion high fidelity FM receiver was perhaps the first FM broadcast monitor. It had a frequency range of 85-115 mHz, and was a redesign of the earlier 44-50 mc model. This is a great-sounding rack-mount unit that weighs a ton and makes the REL Precedent and Marantz 10B look flimsy by comparison. It has several interesting features, including an antenna tuning control, a two-position "mute" switch (not variable), and lots of negative feedback used in the audio stage. It has two meters, one for signal strength (50 uA) and one for center of station.

A type 956 acorn tube is the RF amplifier, followed by a 9002 local oscillator. Plate voltage to the L.O. is supplied by a VR-150 regulator. The tuner uses ceramic tube sockets and a massive tuning cap. The L.O. runs 10.7 mHz below the incoming RF, and a 6AK5 mixer tube then converts it to the first IF of 10.7 mHz. This is then mixed again, via a 6K8 pentagrid converter with a 6.1 mHz crystal oscillator. The difference is 4.5 mHz, which is then amplified by two stages of double-tuned IF transformers, driven by two 6AB7 tubes, and then fed to two more tuned 6AC7 limiters.

A 6h6 discriminator is used, presumably Foster-Seely. Another 6H6 tube is used for the muting/squelch. The demodulated audio is fed to a 6AC7 voltage amplifier, through the bass and treble controls, followed by a 6SL7, 6SJ7, a 6J5 phase splitter to a pair of push-pull 6V6's. A large UTC output transformer is used, and can be strapped to drive an 8 ohm speaker. The unit also has a phono input. A 5U4 rectifier tube is used.

I've never seen another one other than mine. If anyone has a schematic or manual for this unit, please contact me! There's more information on Harvey products here."

That's an intersting site with the rara avis of the tuner world- including REL Precedent- another nice one.

Just a little break from all that needless chrome for the weak and vain and silly buttons for the lazy.

Cheers,

Bambi B

This post is made possible by the generous support of people like you and our sponsors:

Kimber Kable

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