Amps
[Top] [All Lists]

Re: [Amps] Different amp recommendations

To: amps@contesting.com
Subject: Re: [Amps] Different amp recommendations
From: Richard Solomon <dickw1ksz@gmail.com>
Date: Wed, 8 Feb 2012 08:59:11 -0700
List-post: <amps@contesting.com">mailto:amps@contesting.com>
So, all this talk begs the question ....
What is available in the Ham Market that will do 1.5 KW for any length of time.

I expect if such an animal existed, they would be selling a bunch of them.

73, Dick, W1KSZ

On Wed, Feb 8, 2012 at 8:46 AM, Rich <w9cin@comcast.net> wrote:
> I have owned many of the AL-82,  Al-1200,  AL-1500 series amps,, they
> all use the same
> power supply and the same tank ckt.
> did many tests on long time, high output . and found the amp is very
> good, for normal ham use
> but running at 1300-1500 watts out for 10 -15 min the tank circuits got
> so hot the solder got soft.
> asking any amp to do 1500 watts for 30 min. is asking a lot
> that's why they most manufactures rate them as "intermittent amateur
> radio service" .
> just my thought's
> "Rich"
>
>
>
> On 2/8/2012 12:29 AM, Jim Thomson wrote:
>> Date: Mon, 6 Feb 2012 11:47:42 -0600
>> From: Rob Atkinson<ranchorobbo@gmail.com>
>> Subject: Re: [Amps] Different amp recommendations
>>
>> I have doubts about the AL82 doing 1500 watts 100% duty cycle for very long.
>>
>> Knowing the p.s. in that amp you'll be right at its limit, right at
>> the Ip limit of the tubes, right at or a bit above their maximum
>> dissipation...
>>
>> It's a "legal limit" amp only because Ameritron heaped up the Ep.
>>
>> But you can call almost anything "legal limit" with no time factor 
>> considered.
>>
>> Your enemy is time.  do you want to go for 10 minutes or more at 1500
>> w. on RTTY?   Do you want to be able to forget about the amp and not
>> have to look at it nervously every 15 seconds to make sure it's okay?
>>
>> Personally, I like overbuilt stuff.
>>
>> you can beef up the AL-82 in some ways and settle for 1.2 or 1.3 KW,
>> homebrew an amp or keep looking with more money.
>>
>> 73
>>
>> Rob
>> K5UJ
>>
>> ##  let's do the jr high school maths.  The xfmr in the AL82/1200/1500  is
>> rated at 1.8 kva CCS. [32 lb].   To get 1.5 kw out,  we require 1500/.6eff = 
>> 2500w dc input.
>> When those dahl xfmr's are maxed out, the temp rise is rated at 55 deg C 
>> over a 40 deg C
>> ambient.  That also factors in another 10 deg C deep inside the core..for 
>> 'spot heating'.
>> Deep inside the core, it will be 65 deg C over the outside 40 deg C ambient.
>> Now 40 deg C = 104 deg F.   Now the hottest it will get, deep inside the
>> core is 105 deg C  or  221 deg F....which is hot.
>> On CW, with dashes at a 3.6:1  dash to dot ratio, this
>> xfmr will be fine.  RTTY for hrs on end, yeah, I don't think so.  A 46 lb 
>> dahl is only good for
>> 2.7 kva CCS....and that would be the smallest  size I would use in a RTTY 
>> contest.
>>
>> ## If ur eff is lousy on 10m, like 50%... now you require 3 kw dc input to 
>> get 1.5 kw out.
>> IMO, the initial  extra cost of a slightly heavier xfmr is well worth it. 
>>  You save nothing
>> in the long run by under sizing pwr supply components OR tank components 
>> like coils+
>> bandswitch's, etc.  A bigger  xfmr not only runs cooler, it will also have 
>> way better V regulation.
>> IF you burn up a xfmr, it will have to be replaced with the 46+  lb unit 
>> anyway, so now you
>> not only didn't  "save"  any money....you lost money !  IMO, build it [or 
>> buy it]  like a tank,
>> then never look back.
>>
>> Later... Jim  VE7RF
>>
>>
>>
>>
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps

<Prev in Thread] Current Thread [Next in Thread>