my new toy

1iwilly · Sep 28, 2020

well i got lucky today got me a 2 pill base with 2879 I'm seen around 150 out of it for $125.00
and he gave me for free an astatic silver eagle missing cord and bottom plate I had a 4 wire mike cord so i wired it to test it out got it working it has some sort of a beep when key up from the factory

Eldorado828 · Sep 28, 2020

Shoot yeah, can't beat that. Toshiba pills alone are worth that much or more these days!

9C1Driver · Sep 28, 2020

Brings up several questions. I'm thinking that 2879's were probably swapped in as an "up-grade". That would explain why the power is way down, other things in the amp were probably not re-configured for the larger finals. That or maybe one of them is blown. Still a decent find.

S&W357 · Sep 28, 2020

That looks like my Gray 200 base amp...I think. I’ll look in the morning and post a picture. No Toshiba pills in mine though.

You’re gonna like it.

nomadradio · Sep 28, 2020

An old amplifier. Has probably had more than one pair of RF transistors installed in it over the years.

Biggest problem we had was the extra-high power-supply voltage. As much as 23 or 24 Volts on standby. Drops a lot lower than that while it's keyed.

Some 12-Volt transistors take this for longer than others. We adopted the habit of installing a 30-Amp 'cube'-type automotive relay between the power supply and the RF transistors. The coil is wired to operate when the antenna relay is energized. When the main relay closes, the power is applied to the transistors. Since they have drive power, they begin to draw power-supply current immediately, and this holds down the unregulated DC voltage.

On the other hand, if it ain't broke.....

73

S&W357 · Sep 28, 2020

Here's mine...looks like yours 1iwilly. Different pills.

Big Kahuna · Sep 28, 2020

As shown in the photos above that amp was designed and sold with 455's. Looks like someone swapped in the 2879's.

AudioShockwav · Sep 28, 2020

I used a CMI amp like that, unregulated power supply that had MRF 492 transistors in it.
It would float @ 21 volts or so unkeyed.
It had stopped working and the guy told me I could have it.
Replaced the key transistor and a couple caps, ran it for a few days then gave it back to him, he was still using it when I moved away.
I don't think that one had any bias in it, it was years ago, but most everyone down there ran AM back then anyway.

73
Jeff

1iwilly · Sep 28, 2020

the previous owner said the pills were changed to 2879 like 3 years ago

S&W357 said:
Here's mine...looks like yours 1iwilly. Different pills.

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my new toy

1iwilly

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Eldorado828

8-2-8 in the Lonestar state

9C1Driver

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S&W357

$upporting Member KO4RJD....WDX-556

nomadradio

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S&W357

$upporting Member KO4RJD....WDX-556

Big Kahuna

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AudioShockwav

Extraterrestrial

1iwilly

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