No Carl, I just have a stingy reading Bird 43 PEP power meter with needle
stiction and dicky peak-hold time constants...what's a few dB between
friends anyhow? :-)
Australia's archaic and anachronistic Tx power regulations for the amateur
radio service are currently under review to bring them into line with
international norms after a 1 kW trial last year; the stumbling block to
being enshrined into new regs was the perception of Joe Six-Pack ham's poor
understanding of their obligations with respect to EMR issues and human
exposure to antenna fields. That education phase is being addressed by our
WIA national body to the satisfaction of our ACMA regulator.
Cheers
-----Original Message-----
From: Carl [mailto:km1h@jeremy.qozzy.com]
Sent: Sunday, 25 January 2015 12:32 PM
To: Leigh Turner
Subject: Re: [Amps] ceramic vs glass / Eastern Bloc vs USA Tx tubes
So you have no respect for your power laws down there?
Last I read....5 minutes ago....even Advanced is still limited to 400W
--------------------------------------------------
From: "Leigh Turner" <invertech@frontierisp.net.au>
Sent: Saturday, January 24, 2015 8:33 PM
To: "'Jim Thomson'" <jim.thom@telus.net>; <amps@contesting.com>
Subject: Re: [Amps] ceramic vs glass / Eastern Bloc vs USA Tx tubes
>
> G'Day Jim,
>
> In answer to your question my amplifier running the Russian GU-74B tetrode
> / so-called 4CX800 tube is now in its 12th year of faultless service and
> still makes full rated power.
>
> Similarly the amp using its big brother 2500W plate dissipation GU-84B
> tube still makes rated 2+ kW key-down / 3 kW PEP output in its now 10th
> year of faultless service in my shack. Photos can be seen on my qrz.com
> page.
>
> At this rate and anecdotal experience the Russian tubes in regular ham
> radio duty SSB service are likely to see out and outlive its owner; thus
> seem like they're on a trajectory path for ultimately yielding your
> mentioned 20 year service life :-) Now this is entirely consistent with
> expectations in the context they were originally designed as rugged mil-
> spec Tx tubes for the Russian military service.
>
> As I previously mentioned the key to Tx tube longevity in my experience is
> to not abuse them and to always conservatively use tubes within their
> manufacturer's published Data Sheet ratings. The peripheral electronics
> placed around the tube also play an important role in ensuring the tube is
> well cared for and protected under all conceivable adverse conditions.
>
> You're right about rebuilding the bigger broadcast service Eimac tubes and
> repurposing them virtually endlessly; but my Russian AB1 tetrodes were
> also cheap to purchase and have yielded outstandingly good bang for the
> buck. Sadly all good things come to an end as supply of these NOS surplus
> tubes eventually dry up :-(
>
> However the capable and affordable FU-728F Chinese counterpart military Tx
> tube is still in current day production and has become the new benchmark
> for today's high-end ham amplifiers. I commend folk to study it closely.
>
> Cheers,
>
> Leigh
> VK5KLT
>
> -----Original Message-----
> From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Jim Thomson
> Sent: Sunday, 25 January 2015 12:39 AM
> To: amps@contesting.com
> Subject: [Amps] ceramic vs glass
>
> Date: Sat, 24 Jan 2015 12:53:21 +1030
> From: "Leigh Turner" <invertech@frontierisp.net.au>
> To: "'Bill Turner'" <dezrat@outlook.com>, <amps@contesting.com>
> Subject: Re: [Amps] 5 Minutes for Ameritron 811H to warm up?
>
> Personally I wholeheartedly concur with your sentiments here Bill; most of
> my shack amps are of the ceramic tube variety and indeed do seem to last
> forever.
>
> My only exception amp is the venerable Kenwood TL-922 with its nostalgic
> pair of Eimac 3-500Z glass bottles...they too have proven very reliable
> workhorses! The proviso rider with any tube is absence of abuse.
>
> 73
>
> Leigh
> VK5KLT
>
> ## What's the most anybody has gotten out of these russian ceramic wonder
> tubes like GU-74B etc ?? Can you get 20 years out of them, beating on
> em 7 days a week, like an Eimac 3-500Z ?
>
> ## What is longest anybody has gotten out of an Eimac 8877 ??
>
> ## at least with the bigger eimac ceramic tubes, like 3x3, 3x6, 3x10,
> 4x5, 4x10, they can be re-built till hell freezes over, unlike their throw
> away, smaller ceramic siblings. IMO, you get a bigger bang for the $
> with the bigger ceramic tubes, esp since being thoriated tungsten fil, you
> can reduce the fil V way down, like 12% or more, further extending tube
> life. Take a 3x3... rated for 2.5 A CCS plate current...then run it at
> 1.5 to 1.7 A plate current..along with reduced fil V it will last forever.
>
> The typ 2 x 3-500Z amp is rated at 800ma max plate current.... and my L4B
> runs at 800ma...just to get 1290W po.
>
> Jim VE7RF
>
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>
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