I'll take a Henry 3K-A any day.
From: Amps [mailto:email@example.com] On Behalf Of Roger (K8RI)
Sent: Friday, April 24, 2015 9:00 PM
Subject: Re: [Amps] Considering an ALS-1306
It's not who's right, it's who put in components such as the PS that are
capable of running at tilt all day long. With tube amps it's normal for one
that will run the legal limit all day long to be heavier, larger, more
expensive, and capable of running substantially more than the legal limit,
than many, or most "legal limit" amps that are not computer controlled.
With the computer controlling the power they can build an amp capable of
running the legal limit all day long, yet not run far more than the legal
limit on SSB. Of course you pay for that extra capability.
I can think of two reasons for the above. To build a true legal limit tube
amp with no time limit, the amp will likely be capable of 2 to 2.5 KW PEP
(or more) and the FCC might frown on that. The other is "cheap"! They can
claim it's a legal limit amp, which it is for SSB, but derated in other
modes. They can run a lower plate voltage which
also lets them use a smaller and lighter transformer. IOW, the time
limit comes because of the components in the PS and is set by how hot they
are willing to run the transformer.
Of course there is the heat output as well. Ignoring other sources, at 60%
efficient (give or take) you are going to run at least 2500 W input for 1000
watts of heat just from the plate efficiency. AB1 will give you even more.
At 25% class A makes one whale of a space heater!
Some companies sell amps that have a higher output than the tubes are rated
to put out, or they rate them at an output power that will drastically
shorten the life of the tubes, not to mention as to what running them that
way does to the IM. I can run the legal limit all day long with good IM
figures as reported on the air and the transformer only gets warm. With
lots of audio processing with my long winded transmissions, it will kick
into high blower which I hardly notice in the shop, but you better be
wearing a headset in this small den. Since I have operated here in the den
most of the time over the past few years, I have used the amp only a couple
of time because of the noise, but mostly because of the heat. This room
gets uncomfortably warm because of the computers. With the amp, (in the
summer) it gets downright miserable, so as soon as I get the shop
reorganized the amp goes back out! The shop is one air conditioned room the
size of my entire house, so a KW of heat isn't even noticed.
When the THP SS amp, it was quiet, instant on, or nearly so, and instant
band change. I often wish I'd have kept it, although I do like the big amp
(in the shop)
On 4/24/2015 7:50 PM, Kevin Stover wrote:
> On Fri, 24 Apr 2015 18:45:16 -0500
> Kevin Stover <firstname.lastname@example.org> wrote:
> I forgot to add that Ameritron also derates the AL-1500 to no more than
half an hour at full power. Alpha is famous for the "brick on the key".
>> I'll take your word for it.
>> I don't know of any solid state 1KW amp that doesn't derate the power out
for constant key down modes like RTTY, AM, and FM. I believe the KPA 500 is
derated to no more than 15 minutes key down at full power. Maybe the 1306
wil do 600W all day long.
>> On Fri, 24 Apr 2015 16:22:08 -0700
>> Bill Turner <email@example.com> wrote:
>>> Did Ameritron ever state the duty cycle limit for the 1306? I
>>> phoned them on the 1300 and they told me 600 watts for RTTY or other
>>> full carrier modes.
>>> 73, Bill W6WRT
>>> Amps mailing list
>> R. Kevin Stover
>> Amps mailing list
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