Bill W5WVO wrote:
> After reading all the suggestions (serious and otherwise), I am
> left with only one really appropriate and practical option: Leave
> it the way it is.
>
> (a) The tubes ARE graphite anode 3-500Zs, and (b) I do operate
> mostly WSJT digital modes, full carrier 30 seconds on/off, or in
> the case of EME, one minute on/off. So maximum cooling is
> required. I'm not comfortable with slowing down the fan given
> these two realities. I will just have to live with the noise.
>
>
You might want to look at 140mm computer fans. Noise varies from a
whisper to sounding like a turboprop starting up. Surprisingly the
airflow is not proportional to the noise. The 140's are lower RPM, many
are 3 speed, and most move a lot of air. They are all 12VDC and much
quieter than the 120VAC variety. I'm currently sitting within 3 feet of
12 of the things, and although quite audible they are no more noisy than
our forced air furnace/air conditioner.
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=2010090573%201372726540&name=140mm
These tend to run 1000 to 1500 RPM. I'm looking at one that delivers
63.5CFM @ <16dBA and another that delivers 27.2 - 47.8 CFM @ 18 to 22 dBA.
One multi speed the
Noctua NF-P14 FLX 140mm Case Fan - Retail
<http://www.newegg.com/Product/Product.aspx?Item=N82E16835608017>
has particularly good figures at:
* *Air Flow:* Airflow: 64.96 CFM Airflow with L.N.A.: 49.29 CFM
Airflow with U.L.N.A.: 41.93 CFM
* *Noise Level:* Acoustical Noise: 19.6 dBA Acoustical Noise with
L.N.A.: 13.2 dBA Acoustical Noise with U.L.N.A.: 10.1 dBA for
about $30
On some of them you might want to disable the LEDs <:-)), but the one
above is just a multi speed, many blade fan.
> Thanks for all the feedback, guys, both on and off the reflector.
>
> Bill W5WVO
>
>
> ----- Original Message -----
> From: "Bill K2OWR" <k2owr@comcast.net>
> To: "Carl" <km1h@jeremy.mv.com>
> Cc: <amps@contesting.com>
> Sent: Thursday, December 17, 2009 1:09 PM
> Subject: Re: [Amps] Alternative cooling strategies for SB-220?
>
>
>
>> :::: I'm very thankful someone finally called this discussion,
>>
> particularly
>
>> relating to possibly water cooling an SB220 amplifier,
>>
> "impractical"....
>
>> I can think of other words, but I'm new here, so I wouldn't want
>>
> to be
>
>> obscene.
>> BILL
>>
>>
>>
>> ----- Original Message -----
>> From: "Carl" <km1h@jeremy.mv.com>
>> To: "Rob Atkinson" <ranchorobbo@gmail.com>;
>>
> <amps@contesting.com>
>
>> Sent: Thursday, December 17, 2009 15:03
>> Subject: Re: [Amps] Alternative cooling strategies for SB-220?
>>
>>
>>
>>> The SB-220 fan draws air in from the rear and the output is
>>>
> split by the
>
>>> chassis to pass over the socket pins and the glass envelope.
>>>
> It exhausts
>
>>> thru the top and side perforations.
>>>
>>> Remoting a fan is impratical due to the friction loss and a
>>>
> big blower
>
>>> would
>>> be needed.
>>>
>>> Nice to talk about for 3 days but not very practical.
>>>
>>> As I said before, add a resistor or as another said, go back
>>>
> to the stock
>
>>> fan. However graphite anode tubes need the extra air if those
>>>
> are being
>
>>> used.
>>>
>>> Carl
>>> KM1H
>>>
>>>
>>>
>>> ----- Original Message -----
>>> From: "Rob Atkinson" <ranchorobbo@gmail.com>
>>> To: <amps@contesting.com>
>>> Sent: Thursday, December 17, 2009 2:09 PM
>>> Subject: Re: [Amps] Alternative cooling strategies for SB-220?
>>>
>>>
>>>
>>>> Not sure what mode you want to operate (i.e. what duty cycle)
>>>>
> but if
>
>>>> high d/c the duct trick with the blower remoted may have this
>>>>
> problem:
>
>>>> the 220 fan is normally placed in the cabinet in such a way
>>>>
> that air
>
>>>> is drawn in through the p.s. from what I remember of it. If
>>>>
> you run
>
>>>> duct direct to the rear hole next to the RF deck, you loose
>>>>
> that p.s.
>
>>>> cooling through the v.doubler and B+ transformer. But I have
>>>>
> no idea
>
>>>> how hot the p.s. gets under normal condx or if it gets hot at
>>>>
> all.
>
>>>> Another thing you can try is a tx keyed relay switch on the
>>>>
> power line
>
>>>> to the fan that bypasses a resistor on tx but is n.o. so the
>>>>
> fan power
>
>>>> goes through a voltage dropping resistor to slow it down so
>>>>
> it is only
>
>>>> full speed and noisy when you are transmitting. You have to
>>>>
> wire it
>
>>>> so the fan is not powered in series with one side of the B+
>>>>
> primary
>
>>>> (if that is the stock SB220 arrangement). If you make a
>>>>
> long RTTY or
>
>>>> SSTV tx and the tubes get real hot you will need to use a
>>>>
> timer relay
>
>>>> with a set delay time so the fan speed drops around 30
>>>>
> seconds after
>
>>>> you switch to rx.
>>>>
>>>> Just some ideas.
>>>>
>>>> 73
>>>>
>>>> Rob
>>>> K5UJ
>>>> _______________________________________________
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>>>> http://lists.contesting.com/mailman/listinfo/amps
>>>>
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