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Re: [RTTY] Amp/Temp

To: Courtney Judd <k4wi@k4wi.net>
Subject: Re: [RTTY] Amp/Temp
From: Rudy Bakalov via RTTY <rtty@contesting.com>
Reply-to: Rudy Bakalov <r_bakalov@yahoo.com>
Date: Sat, 7 Oct 2017 11:21:22 -0400
List-post: <mailto:rtty@contesting.com>
I’d venture to guess that the answer largely depends on the quality of the 
materials used in a particular amp.

That said, here’s my experience with a similar amp, 2 x GU74, based on the old 
Alpha 91 platform:

During the recent CQ WW RTTY, the exhaust temp fluctuated between 47C at night 
and 52C during the day when the shack temp was 27C. Mostly running rather than 
S&P. The fan was running at the lowest speed and barely audible.

Rudy N2WQ

Sent using a tiny keyboard.  Please excuse brevity, typos, or inappropriate 
autocorrect.


> On Oct 7, 2017, at 10:58 AM, Courtney Judd <k4wi@k4wi.net> wrote:
> 
> I am looking for any ideas or your thoughts on what would be the safe or 
> maximum operating temperature of a HF amplifier in rtty operation. My setup 
> here is a FT5000 driving an Alpha 86 to about 1200 watts on rtty.... it will 
> do considerably more on cw/ssb and rtty but I felt that I should limit it on 
> rtty. What started all this is that after about 20 years of just sitting up 
> on the shelf doing it's thing, I decided to take the 86 apart and give it's 
> internals a good cleaning. Sure enough, the dust bunnies had been doing their 
> thing. Gave it a good cleaning but when i went to put it back together i 
> noticed that on the back panel where the air enters the amp there was a 
> pre-made place to install a fan. I put a 115 v fan to push air into the amp 
> which goes past the transformer then into the fan below the tubes and then 
> out the top thru the tube shields. On top over the vent holes I built a 
> Styrofoam box with two fans to help pull the air out. Sorta a push-me-pull 
> setup. I bought a couple of digital thermometers with sensors. I placed the 
> probe in the airstream coming out of the amp over the fans in the Styrofoam 
> box and the other the air coming out of the 5000. This is where it got 
> interesting. On rtty when running the 5000 would get up to about 103 deg F. 
> from a resting temp of 79 deg. The amp would go from 90 deg up to a high of 
> 155 deg which sorta made me nervous. I asked my wife if eggs would fry at 155 
> and she said probably! SO, do you guys monitor your amp's temperature and 
> what do you all think is save? Sorry to be so long winded but I am curious! 
> thanks and 73's Cort K4WI
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