My Dad, built several amplifiers, one was a pair of 813s. During his
career in the Air Force, he belonged to MARS, and a lot of parts came
through that system. My brother, W6IJ, and I spent a lot of our time at
the Travis AFB MARS station. We cut our ham radio teeth there. Learned
the code, basic electronics. Ham radio became the "thing" that us boys
did together.
I remember coming home from overseas and seeing the 813 amplifier. It
was UGLY, a real hodge-podge of repurposed former military cabinetry. It
was reasonably safe, but the power supply was another thing. He had it
under the table and the components were exposed. The bleeder resistor
was exposed on top of the power supply where if you weren't careful, you
could get your feet in a perilous situation.
I couldn't stand for that and while I was home on leave I built a cover
for the power supply. Dad just couldn't see the need for it. His premise
was that he was the only operator, knew the power supply was there and
so he didn't think it was a big deal.
That amp worked very well, and offered switchable biasing for AB2 and C
class. Dad, WQ6H, loved CW, so it HAD to have class C capability.
That amp/power supply had a 115 VAC transformer in it, so it dimmed the
lights throughout the house when he keyed it. Luckily, our nearest
neighbors were about a 1/4 mile away. Nonetheless, I'm pretty sure they
all knew when Dad was on the air. TV was unwatchable in our house when
the rig was operation.
These days, we're pretty spoiled by advances in technology, both in ham
radio and in TV. The advent of cable and satellite has made the
likelyhood of interference much less of a problem.
Chuck, W6AJW
On 01/13/2017 11:42 PM, Fuqua, Bill L wrote:
As a teenager I too built unshielded amplifiers.
I just wanted to get results and then do something else.
I got my general in 1962 or 63. don't recall.
My first HB rig was a 6AG7,6L6 and pair of 6146Bs on CW. I then went to SSB
with a CE 10A which drove my
6146Bs, and later I made a amp with a pair of 813's and then went to a pair of
grounded grid 250th tubes.
The HB transmitter was shielded but the amps were not.
73
Bill wa4lav
________________________________________
From: Amps [amps-bounces@contesting.com] on behalf of Russ Williams via Amps
[amps@contesting.com]
Sent: Friday, January 13, 2017 10:36 PM
To: Arnie Pfingst; amps@contesting.com
Subject: Re: [Amps] home brew amp
Arnie, thank you for posting this. I am glad to hear there were others whose
audio came into the neighbors stereos and scrambled TV reception. I didn't
have the opportunity to become a ham during my school years, so I went the CB
route and built 11 meter sweep tube amplifiers from my high school junior year,
1973 and forward, finally getting my novice ticket in 1985. I am still
building today and play with regens and am sorting out a 4-400A 6 meter amp I
built a few years ago.73,RussKW6T
From: Arnie Pfingst <arnie123@hotmail.com>
To: "amps@contesting.com" <amps@contesting.com>
Sent: Friday, January 13, 2017 3:13 PM
Subject: [Amps] home brew amp
I've been reading about how several people on here built an amp and how it
works or doesn't work
I had my General Lic. before I graduated H.S (1972). I thought I was good with
electronic design and knew everything about building stuff.
My station was all, Heathkit SB 300 receiver, SB 401 transmitter, SB 600
speaker, monitor scope, antenna tuner, EV desk mic, and phone patch.
Not bad for a kid just out of High School. I thought the only thing missing was
an amplifier. My dad suggested I build one, (he worked CW in the spark gap days
his call was 9ccj)
so I did.
I found a pair of new 813 tubes on the old 40 meter swap net, and scrounged all
of the the parts needed for a separate power supply that sat on the floor.
When it was done, I think it put out about 500 watts into a wire. I got my WAS
and WATV in one weekend!!! (worked all stereos, and worked all TV) I was proud
of my accomplishment,
it all worked. Shielding? i didn't have money for that so the tubes just sat on
top on the chassis directly in front of a small blower. My dad was ready to
kick my ass for doing this after he had words with most of the neighbors. My
point is to encourage people to continue building and TRYING things.
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