Whoa... I guess EBay doesn't have them listed anymore...
But Harbach has some.
https://harbachelectronics.com/shop/drake/res-400-5-pack-of-hv-safety-resistors/
73
Jim W7RY
-----Original Message-----
From: Jim W7RY
Sent: Wednesday, November 15, 2017 7:08 PM
To: Jim Thomson ; amps@contesting.com
Subject: Re: [Amps] Glitch resistor + fuse?
I'm pretty sure they are .82 Ohms at 2 watts. There are lots of them on EBay
for free shipping and small quantities.
73
Jim W7RY
-----Original Message-----
From: Jim Thomson
Sent: Wednesday, November 15, 2017 1:15 PM
To: amps@contesting.com
Subject: [Amps] Glitch resistor + fuse?
Date: Wed, 15 Nov 2017 09:49:54 -0600
From: "Doug Renwick" <ve5ra@sasktel.net>
To: <amps@contesting.com>
Subject: [Amps] Glitch resistor + fuse?
<The Tentec Titan amp uses a single 10 ohm 25watt ohmite.
<Doug
## with say 1.5 A of plate current, that amounts to 22.5 watts diss, so it
will work ok.
But 10 ohms doesnt limit the fault current to a low value. 2600 divided by
10 = 260 A fault current,
which is still a bunch. 2600 divided by 50 ohms = 52 A fault
current..which is a lot less obviously.
Anything is better than nothing of course.
## Forgot to mention in my previous posts, re protection diodes. I use
several 6A10 s in parallel, to
make one big diode. 3 or 4 of the 6A10s, each with a 400A surge rating,
albeit only for 8.3 msecs,
is then good for 1200-1600A. With out any HV fuse in there to interurpt
the fault current, it can take
a while for the breaker in the 240 vac line to open up. The HV filter C,
plus the value of the glitch Resistor,
form a simple RC network.
## eg. 25uf and 10 ohms = .00025 secs. = .25 msec
25 uf and 50 ohms = .00125 secs = 1.25 msecs
100 uf and 50 ohms = .005 secs = 5 msecs
## and thats just the time it takes to partially discharge the filter cap
down to just 36.8 % of the original B+ voltage.
Jim VE7RF
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