I need to correct myself. I was reading data from the MFJ-974 tuner.
Perhaps MFJ should include a cooling fan!
However, even higher losses occur on 10m with the Palstar AT4K.
Paul, W9AC
----- Original Message -----
From: "Paul Christensen" <w9ac@arrl.net>
To: <amps@contesting.com>
Sent: Wednesday, March 09, 2011 12:49 PM
Subject: Re: [Amps] New Alpha 8410 photos + Video
> That's just a bit more than 10% of maximum delivered power and cabinet
> ventilation openings should provide ample convection. Take for example
> the AT4K ATU. Into a 1:1 resistive 50-ohm load on 40m, loss is 32%
> (1.67dB) as measured by the ARRL. That's not some extreme load -- and
> it's just one example from the manufacturer's C-L-C tuners.
>
> The same tuner also shows high loss on the low bands under conditions of
> low load Z. That's an indication of insufficient output C for the job.
> Classic C-L-C tuner loss is primarily attributed to marginal coil Q across
> the operating spectrum, poor cabinet layout around the coil, and
> insufficient output C with low Z loads. In order for the high loss to
> occur on 40m into a 50-ohm load, there's some quirk in the AT4K design
> that the manufacturer has decided to address with a cooling fan rather
> than attacking the root cause in the design phase.
>
> Paul, W9AC
>
> ----- Original Message -----
> From: "Paul Playford" <paul@w8aef.com>
> To: "'Paul Christensen'" <w9ac@arrl.net>; <dezrat1242@yahoo.com>;
> <amps@contesting.com>
> Sent: Wednesday, March 09, 2011 12:08 PM
> Subject: RE: [Amps] New Alpha 8410 photos + Video
>
>
>>I have designed and built a 20m 1.5 Kw bandpass filter that has .4 dB
>> insertion loss.
>>
>> After 30 seconds at 1.5 Kw it gets HOT!
>>
>> .4 dB loss from 1.5 Kw is 165 watts. When was the last time you grabbed
>> a
>> 165 watt light bulb after it has been on for 30 seconds?
>>
>> Time to install a cooling fan.
>>
>> de Paul, W8AEF
>>
>> -----Original Message-----
>> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
>> Behalf Of Paul Christensen
>> Sent: Wednesday, March 09, 2011 9:36 AM
>> To: dezrat1242@yahoo.com; amps@contesting.com
>> Subject: Re: [Amps] New Alpha 8410 photos + Video
>>
>> True, but I'm referring to their past ATU designs with cooling fans.
>>
>> Paul, W9AC
>>
>>
>
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