You get the same bandswitch even in the latest Alphas and they also used
similar anode clips in the past.
Carl
KM1H
----- Original Message -----
From: "Paul Christensen" <w9ac@arrl.net>
To: <audioguy@q.com>
Cc: <amps@contesting.com>
Sent: Wednesday, April 06, 2011 6:48 PM
Subject: Re: [Amps] Alpha vs Henry
> I've never run into any 160m toroid heating issues with my 70V. It's runs
> approximately the same class of service as the 77. However, I did have a
> an
> RF arc issue that required placing the toroids about a quarter-inch away
> from the mounting surface.
>
> I've never used the AL-1500 but have seen the inside components countless
> times at various hamfests. Given the marginal quality of many RF
> components, its a testament to the overall design of the AL-1500 since I
> believe few have operation issues. Still, it pains me to see Airdux
> coils,
> small ceramic band-switch wafers, sheet metal construction, weak
> mechanical
> anode cap, low industrial-grade blower, etc.
>
> Paul, W9AC
>
> ----- Original Message -----
> From: "Jim Barber" <audioguy@q.com>
> Cc: <amps@contesting.com>
> Sent: Wednesday, April 06, 2011 6:33 PM
> Subject: Re: [Amps] Alpha vs Henry
>
>
>> Interesting side-thread. I've been thinking about replacing my
>> black-faced Alpha 77 with an AL-1500, primarily because the Alpha
>> doesn't have 160 and I don't like the nature of the "upgrade" to put it
>> in. (My "yellow-faced" PA77 has the 160 mod but I'm afraid to run RTTY
>> or even full-power AM because I'm paranoid about the toroids)
>>
>> 73,
>> Jim N7CXI
>>
>> On 4/6/2011 3:22 PM, Roger (sub1) wrote:
>>> On 4/6/2011 5:05 PM, Al Kozakiewicz wrote:
>>>> Can anyone tell me how much power an AL-1500 is rated to produce at a
>>>> 100% duty cycle?
>>>>
>>>> During RTTY contests and outputting about 1000 watts, the tube side of
>>>> the cabinet gets mighty warm.
>>>
>>> It should. Running 100% duty cycle and 1500 watts out at 60% efficiency
>>> means you are dissipating 1000 watts. That is a LOT of heat. The temp
>>> of the exhaust air depends on how much air (CFM @ however many inches of
>>> H20) the fan can push. The 8877 is a relatively small tube for its
>>> ratings, but it has a fairly efficient radiator. OTOH that means a
>>> blower that can produce a fair amount of back pressure is required to
>>> get full output from the tube.
>>>
>>> As a comparison, when I had an all electric house I heated the basement
>>> and ham shack with 4400 watt space heaters mounted in the walls. In the
>>> dead of winter it only took a few minutes to heat the 13 X 21' den to
>>> about 70 degrees. After that the heater would only kick on a few times
>>> for only a few minutes per hour. That means your amp running under these
>>> conditions puts out enough heat to require opening the den door to keep
>>> a reasonable temp. IOW you could heat a good sized room with that amp
>>> on RTTY.
>>>
>>>> The power supply side seems cool - but then, that's with the cover on.
>>>> I don't know how hot is too hot and it would be useful to know at least
>>>> how much continuous power the supply is rated for.
>>>
>>> If you were running large glass tubes that depend on radiation that
>>> cabinet would be too hot to touch.
>>>
>>> 73
>>>
>>> Roger (K8RI)
>>>
>>>> Tube cooling is probably another issue...
>>>>
>>>> Al
>>>> AB2ZY
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>>>>
>>>
>>>
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>>
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