I am curious - do MRI still use tubes or are they mostly solid state
power-amplified now? Most of the elemental analysis (still-called NMR) use VHF
SS PAs. I like the 8877/3CX1500A7. Its a great triode, have designed into
amplifiers at 1.5 kW CW (class C) at 108 MHz. I have one here in a plasma amp
that I used for various tests of materials at HF, 1-2 kW CW. Very simple to
bias and use as a linear tube.
Randy, AB9GO, explained why tube-based MRI amplifiers don't wait until tubes
degrade. I can think of another reason that is of importance. Liability. If a
medical machine miss-diagnoses something important, due to equipment
malfunction, the implications are tremendous to both the patient and the
provider. My wife works as a NP in a private practice and reminds me often of
the types of severe illnesses that they deal with day to day. Any mistake can
be a disaster for all. I believe that X-RAY tubes are also exchanged on a
frequent basis. It has nothing to do with insurance companies or the federal
gov't paying. That comment is actually a loaded political statement that has
little to do with AMPs or their technology here.
73
John
K5PRO
Message: 2
Date: Wed, 01 Aug 2012 13:04:35 -0700
From: "Bill, W6WRT" <dezrat1242@yahoo.com>
Subject: Re: [Amps] 3CX1500A vs el cheapo GS-35B
To: AMPS <amps@contesting.com>
Message-ID: <de2j18pjf2vn2fer0uvjioon4p8u6nvenk@4ax.com>
Content-Type: text/plain; charset=us-ascii
ORIGINAL MESSAGE:
On Wed, 1 Aug 2012 14:10:57 -0400, Randy wrote:
>The timed replacement is to prevent downtime not to waste
money just because someone else is paying the bill. Its purpose is to save big
money. Think about it. At $2000 a study, 3 per hour (or more) and an average
12 hour working day = $72,000 per day gross lost if the MRI is down not to
mention the separate loss to the Radiologist who are not making money since
there are no MRI studies to read. Radiologists get incensed (in about 1 micro
second) if you mess with their income. I know this from personal experience.
Don't forget the patient who now has to reschedule their appointment. The
manufacturer knows where on the tubes failure rate curve that the sweet spot
between replacement cost and downtime exists. I have worked with Radiology
techs on equipment before and no one wants to hear that any modality is
non-functional if it can be prevented.
>
>
>Randy E. Randall AB9GO
>Network Engineer
>UC Health
>Randy.Randall@UCHealth.com
>Phone 513-585-7146
>Fax 513-585-7159
REPLY:
Everything you say confirms what I said. Everyone - not just the MRI makers -
could not care less about cost when either insurance or the gummint is paying.
If the MRI makers wanted to, they could make a quick-change module that anyone
could swap in about two minutes when the red light comes on. They're not
interested.
And that's only the beginning. It's just not a priority when money flows like
water.
73, Bill W6WRT
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