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Re: [Amps] RF Parts OEM 3-500ZG's

To: "Michael Tope" <W4EF@dellroy.com>, <amps@contesting.com>
Subject: Re: [Amps] RF Parts OEM 3-500ZG's
From: "Mike Schatzberg" <cherokeehillfarm@earthlink.net>
Date: Mon, 08 Aug 2005 08:58:36 -0400
List-post: <mailto:amps@contesting.com>
Hello Amp Fans:

I had purchased new tubes years ago from Pride, which were manufactured in 
China, and marked PRC, People's Republic of China.  I used them in an SB 220 
for many years, after making a few changes to the amp, including changing 
the strapping of the grids to ground.  The tubes produced 1.5 KW with about 
80 watts drive, and worked dependably, although I also increased the cooling 
by about 30% on the pins and glass.

Since that time I have rebuilt many more amplifiers, and purchased new 3 - 
500 ZG tubes, RF Parts brand, in matched pairs.  The internal parts, look 
identical to the earlier Pride tubes, as do all other aspects of the 
triodes.  The serial number codes look like the same system and the method 
of application also look identical to the Pride.

All of these tubes have worked flawlessly.  I think it is a good idea to 
purchase the matched tubes, because I believe the matching, although not 
done dynamically under load, means that RF Parts themselves have checked the 
tubes before shipment.  Just one more chance to catch a defective unit 
before it gets to you is worth something.

According to the information and the early spec sheets I have for the Eimac 
tantalum vertical finned and graphite donut anode types, RF parts tubes are 
higher mu, about 160, as compared to about 110.  The Amperex licensed French 
tubes, which are so expensive, are also lower mu.

I don't know why RF Parts doesn't publish spec sheets for the tubes, but I 
guess they really don't want us to know their sources for them.  Pride was a 
major Chinese manufacturer, and a maker of better quality.  I do not know 
much about the company today, or if they still use their own branding 
anymore.

73 and Happy Dxing,

Mike Schatzberg
WB2AJI


----- Original Message ----- 
From: "Michael Tope" <W4EF@dellroy.com>
To: <amps@contesting.com>
Sent: Monday, August 08, 2005 12:54 AM
Subject: [Amps] RF Parts OEM 3-500ZG's


>I just bought a used Ten-Tec Centurion on behalf of a friend. We
> both were under the mis-informed belief that it would be equipped
> with Eimac 3-500ZG's. Instead it has a matched pair of RF Parts
> branded PRC manufactured 3-500ZG's. Anybody know the track
> record of these tubes compared to the Amperex 3-500ZG (made
> in France?) or the ones Eimac used to make?
>
> Thanks,
>
> Mike, W4EF..................................................
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