[Amps] Considering an ALS-1306

[Roger (K8RI)]

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)

73

Roger  (K8RI)



On 4/24/2015 7:50 PM, Kevin Stover wrote:
> On Fri, 24 Apr 2015 18:45:16 -0500
> Kevin Stover <kevin.stover at mediacombb.net> 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". Who's right?
>
>
>> 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 <dezrat at outlook.com> wrote:
>>   
>>> REPLY:
>>>
>>> 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
>>> Amps at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>
>> -- 
>> R. Kevin Stover
>> AC0H
>> _______________________________________________
>> Amps mailing list
>> Amps at contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>


---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com