Some joke, Peter. ?One failure in nearly 20 years.?
The HRC fuse has blown twice during that time - once when the top band antenna broke and once when a gamma matched beam flashed over.
It¡¯s not perfect, I¡¯ll concede that.?
On Monday, December 2, 2019, 8:08 pm, Peter Voelpel <dj7ww@...> wrote:
It?s an expensive fuse, not more.
To install it as an rf choke into a 3CX3K
amp must be a joke.
?
73
Peter, DJ7WW
?
?
The
choke is a lot more robust than you would think.? I've had a couple of
them pop over the years but tracked that down to a resonance (AKA idiot builder
error) each time.? Fix the resonance (reposition), patch the choke and
back in biz.? The size of the choke wire from a "can it carry the
plate current" standpoint is definitely fine for typical use - unless you
are in the fire breathing realm.?
If
you don't believe it and want to feel better about it, hang a few sizes of mid
30's gauge wire on a constant current supply and see how just high you have to
bump that current to get it to open up.? You may be surprised.
73/jeff/ac0c
alpha-charlie-zero-charlie
?
?
On 12/2/19 10:13 AM, cturnertuning wrote:
This
confirms your choke is the "fuse" in your amplifier. If you are ok
with that Dave, then great. I have one in an AM plate modulated amplifier with
a pair of 4-400s modulated by a pair of 304TLs. The choke has survived. I have
had failures but was running them past the ratings. Did your choke
unravel?? That seems to be the type of failure with these. One good bang
and they un wind on the form.
C
On 11/30/2019 7:15 PM, DAVE WHITE via Groups.Io wrote:
¡°Ratings are guidelines¡± - yeah that what
this guy at Essen Motor Show said this weekend (picture attached)?
In my 3CX3000A7 amp I used a very similar choke (in
fact it looks the same) bought from RF Parts. ?I think it too is rated at
4kv 1.5A. ?
I¡¯ve had one failure in 18 years with the amp
and that was the choke. ?I use a glitch resistor and an HRC fuse inthe
?HT line which worked fine and protected the amp when the insulator at the
end of my top band 3/8 inverted L exploded one night, thus leaving the choke
ok. ?But one day about 10 years ago the choke just went BANG. ?I
never worked out why. ?I replaced it with another identical one and (touch
wood) it¡¯s been ok since.?
I know that B&W used to make a much higher rated
choke years ago but they seem to be unobtainium now. ?I run 5.5kv resting
voltage on the anode so always knew that the plate choke was the weakest
point.?
That looks like a nice amp in the pictures.
I used two rollercoasters and two vacuum capacitors as
a Pi-L 10-160m, by the way. ?
I bought a mix of A7 and
F7 tubes from the Dayton flea market so bought an A7 socket and removed the
filament rings and flying leads from the F7s with a little heat. ?They¡¯re
just held on there with soft solder. ?The idea was that a tube change is
much easier.?
73 Dave?
On Sunday,
December 1, 2019, 2:30 am, Carl <km1h@...> wrote:
Yep, while the designer ran a full bore 2 hole AL-1500
with no problems the company went to a lower rating to minimize warranty
issues.
Note I also stressed the layout as many Hammy Hambone
amp builders havent a clue about coupling and "parasitic"
resonances..Not AG6K parasitics!?
----- Original Message -----
Sent: Friday,
November 29, 2019 12:27 AM
Subject: Re:
[ham-amplifiers] 3CX3000F7 10-80m
Ratings are guidelines.
73, Alek
VK6APK
On 29/11/2019 10:14 AM, cturnertuning wrote:
Not really. Its rated at 4kv max and 1.5 amp peak. It
is the weak link for sure. But if it works it works. Better have a glitch. One
arc and its done. In this example its a fuse.:)
Sent from my T-Mobile 4G LTE device
The Ameritron choke will easily handle 2A?from
that tube on CW and SSB.
It is also well placed for minimum coupling.
----- Original Message -----
Sent: Wednesday,
November 27, 2019 10:40 AM
Subject: Re:
[ham-amplifiers] 3CX3000F7 10-80m
That
little Ameritron plate choke is screaming for its life :) Very cool amplifier!
?
On 11/26/2019 6:53 PM, Mike via
wrote:
My latest amplifier.![]()
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--
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Clark Turner
480-695-2898
???
?
--
>From sunny Binningup
?
?
?
Family Businesses:
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The Velvet Fox.
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--
Please let me quote you for your parts needs!
I offer a discount on Protunes with parts order!
Clark Turner
480-695-2898
