[TowerTalk] VA6AM triplexer and BPFs

Dave Hachadorian k6ll.dave at gmail.com
Mon Apr 23 23:29:00 EDT 2018

I just installed the very same system at W7WW's last Friday.  He 
also got the 100 cfm fan on the 10 Meter BPF because his antenna 
has a 2:1 SWR at 28.0, and he is a RTTY guy.   He also has the 
system installed in the shack, right behind the operating table. 
The three 50 cfm fans are not loud at all.  They are set to come 
on whenever he turns on one of the AL-1500 Amplifiers.  With the 
noise generated by the AL-1500 blowers, and with headphones on, 
the three 50 cfm fans are not audible.

The 100 cfm fan is a totally different story.  It sounds like a 
Hoover vacuum cleaner, and overrides all of the other noises in 
the shack, including the window AC unit.  We have it wired to the 
10 meter position of the Six-Pak selector switch so that fan 
comes on only when 10 is selected.  You can ask Pavel what the 
thinks, but I would really try to get by with the 50 cfm fan.  I 
think I saw a blurb where K3LR says the 100 cfm was too loud, and 
reduced the voltage to 10-11 volts.  Now that I think of it, 
W7WW's Astron is set to 14.5 volts, so maybe we will also try 
reducing the fan voltage with a few diodes or a resistor.

Dave Hachadorian, K6LL
Yuma, AZ

-----Original Message----- 
From: Bill via TowerTalk
Sent: Monday, April 23, 2018 2:05 PM
To: TOWERTALK at contesting.com
Subject: [TowerTalk] VA6AM triplexer and BPFs

Thanks to all who responded to my questions on triplexers and 

To the guys using the high power VA6AM...

I'll be solely SO2R, never M2.  So only one signal on the air at 
a time....legal limit (really)  The smaller fans are what I'm 
getting on the BPFs except for 10 M.  On 10 I'm getting the 
bigger one which I believe is 100CFM.  I know the smaller fans 
are pretty quiet, but the larger one is pretty noisy.

Any thought s as to the necessity of the bigger fan for 10  and 
how noisy are the fans?  The whole set up will be under the 
operating desk in the kneehole.


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