Re: [Amps] Air temps leaving the amp.

["Carl" <km1h@jeremy.mv.com>]

Probably the same way Amp Supply did it with the LK-800A in the mid 80's. A 
thermal switch mounted inside the silicone rubber chimney and a wirewound 
resistor to the EBM Papst fan.
Carl
KM1H


----- Original Message ----- 
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
To: <amps@contesting.com>
Sent: Monday, February 03, 2014 6:53 PM
Subject: Re: [Amps] Air temps leaving the amp.


> On 2/3/2014 10:33 AM, Al Kozakiewicz wrote:
> > Yes, that is the defining characteristic of an induction motor!
> >
> > The only way to vary the speed of such a motor is either by changing the 
> > frequency of the power source or with a variable speed transmission.
> How does Emtron do it?  They use a sensor in the exhaust, just above the 
> tube and there is a substantial difference between high and low speed.
> When that thing kicks into high it is not quiet.
>
> 73,
>
> Roger (K8RI)
>
> > Al
> > AB2ZY
> >
> > ________________________________________
> > From: Amps [amps-bounces@contesting.com] On Behalf Of Jim Garland 
> > [4cx250b@miamioh.edu]
> > Sent: Monday, February 03, 2014 10:24 AM
> > To: 'Roger (K8RI)'; amps@contesting.com
> > Subject: Re: [Amps] Air temps leaving the amp.
> >
> > This raises an interesting issue. How does one reduce the impeller speed 
> > on
> > a blower with a 120 VAC motor (capacitor start)? I've done some tests on
> > several blowers (3370 rpm) and find the rpm doesn't vary appreciably as 
> > the
> > voltage is varied over a significant range. Once the voltage gets low
> > enough, of course, the blower stalls, but the rpm doesn't vary with the
> > voltage. I suspect this is an inherent property of induction motors. I 
> > first
> > discovered this effect years ago when I tried to reduce the blower speed 
> > of
> > a Rotron blower in an 8877 amp. I switched in a 24V transformer to lower 
> > the
> > voltage from 120V to 96V, but discovered it didn't make much difference.
> > 73,
> > Jim W8ZR
> >
> > > Find what
> > > blower speed gives the required pressure. Then back off to where the
> > > noise is comfortable. Use a sensor in the output air so when the temp
> > > rises it can kick into high blower.  Use a couple sensors to give more
> > > leeway. Normal, high, and afterburner.  IOW.  If a little more speed
> > > will keep the temp in range on SSB, there is little reason to run more
> > > pressure than required, but when heavy duty work like digital or slow
> > > scan heats things up, then go for max cooling,
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
>
> ---
> This email is free from viruses and malware because avast! Antivirus 
> protection is active.
> http://www.avast.com
>
>
> _______________________________________________
> 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