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Re: [Amps] New Amplifier

To: Amps group <amps@contesting.com>, Bill Turner <dezrat@outlook.com>
Subject: Re: [Amps] New Amplifier
From: Catherine James <catherine.james@att.net>
Reply-to: Catherine James <catherine.james@att.net>
Date: Mon, 10 Apr 2017 01:54:42 +0000 (UTC)
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Bill Turner <dezrat@outlook.com> wrote:
> I can think of several ways where transistors are superior to tubes:
 
> 1. When not abused, transistors are far more reliable than tubes.

My SB-220 still has Eimac tubes in it.  I suspect they are the 40 year-old 
originals, though I cannot prove it.  Tubes should last a very long time in 
routine amateur service.

It will be interesting to see how long my 811's last; they been used off and 
for over six months without any change in performance.  Ask me again in a 
couple of years. When they do go, I can spend a few bucks and change them 
simply by plugging and unplugging them in sockets.  Can you change the 
transistors on the heat sinks in the sold state amps as easily?

> 2. Safer. A 50 VDC supply is essentially harmless. 3 kV will kill you 
> instantly.

Can't argue with that.
 
> 3. No expensive filament transformer needed. 

Instead, you need an expensive auto-tuner and protection circuitry, whereas a 
tube radio is fine with a manual transmatch.  I use an ATR-30, which will tune 
just about anything.
 
> 4. A 1500 watt transistor is cheaper than a 1500 watt tube. 

Fairly meaningless given the expected lifetime of both (very long). What 
matters is up-front cost and ease of replacement when needed.
 
> 5. No warm up time.

The warm up time of my 811 and 3-500Z amps is essentially zero.
 
> 6. The amps you mentioned are not rated at 100% duty cycle at 1500 watts of 
> carrier (RTTY, FM, etc.) The PowerGenius XL is (ICAS).

As I and others said, if this amp were capable of 100% duty cycle CCS (not 
ICAS), the additional cost would make more sense.

A $7K amp is at least $3K more expensive than a comparable tube amp.  It's hard 
to see where any of the above would justify the extra $3K.

73,
Cathy
N5WVR
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