The AM Forum

How many things can you find wrong with this?  :P

http://cgi.ebay.com/813-TUBE-HOME-BUILT-HF-AMPLIFIER-PROJECT_W0QQitemZ140326350708QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item20ac1a2f74&_trksid=p3286.c0.m14&_trkparms=65%3A15%7C66%3A2%7C39%3A1%7C240%3A1318%7C301%3A0%7C293%3A2%7C294%3A50

I count at least 35 levels of stupidity just looking at the pictures.  ::)

Derbio,
Your sure find the good ones.

What a waste of a perfectly good jack-bar.
.... and copper cut "especially for you" at exactly 27.185
The builder must have really felt special when that coil came in the NewNitedStates mail, direct from Coke-Labs (tm).

-And where else will you find such a robust array of female 117 sockets, a shocking battery if I've ever seen one.

I'm... speechless.  At first glance it looks like the usual homebrew adventure, but... when you study it, the thing looks like it came from Superman's "Bizzaro World". I love the nice inductive power resistor in the parasitic suppressor. It would be interesting to see what would happen to this thing if it was finished up and "smoke tested". Where would the first cloud of smoke appear?

Youse guys are tooo harsh!   At least give the lad credit for the exceptional effort with regard to the mil-spec green cable lacing above and below deck!  ;)

The RF feed to the tank goes THRU the plate choke instead of offa the plate  ;D

heheheh, Yep, you're right about the RF choke connection, Johnny. That rig must have been a bomb when he fired it up.  The wirewound parasitic suppressor is also a common mistake.  The RF has no chance of getting through those two coils, especially on 11M.... ;D

The guy seems to have a flair for doing decent metal work. If all the wire and connections were stripped out, it could be a good carcass to start a new project.


T

Gee, the front panel doesn't look too bad.  Hell, I've seen much worse insofar as homebrew construction goes. Can't blame the guy for at least building something nowadays, no matter how bad.

He rates an A for effort, and an F for design in my book.

73,

Bruce

It reminds me of the Wawasee Black Cat, JB-75. A single beam power tube loading into a C-L network, with no loading cap required and very broad performance due to the large L. The dimension and shape of the tank coil directly reminds me of the aforementioned CB linear. But this one is bigger and offers tuning or loading (which is it? -what a mess) where the Black Cat required none (fixed). I am -sure- it must be for 10M. No one would dare build an 11M linear.

I could be wrong though - recall the ARRL handbook's "single band kilowatts" - amps that used 813's and the tank was tapped in the middle for the tuning cap.

The lead from the plate supressor is long. But probably not long enough to constitute a tuned line where an 813 is concerned.

might be good for parts to start over. Nothing wrong with the tube locations? 866's seem to be mounted on a plastic sheet then the chassis- that is going to pop.. No place for the loading cap. I think it should have one, Wawasee's ingeniousness  notwithstanding.

The Black Cat was a pretty cool mobile amp for CB.  Reminds me of a friend who ran one ( a pair of tubes?) in 1979 that would do about 200w carrier with huge positive peaks, like 175%.  He wud get on the highway and do a great job imitating truckers, right down to the bounce that modulated his voice. He was always screwing with them.

One day he got on channel 19 and said all truckers are homos and the USA needed to get the rail service going again.  There was chaos on frequency with all the swearing. He spotted a guy in a red Camaro and told the truckers if they wanted to make something of it he was in that red Camaro.   He tells me the poor bastard got cut off a few times and had to pull to the side of the road to escape the lynch mob...  ;D

T

 ;D ;D ;D ;D ;D ;D ;D ;D :P

I never did anything like that.  ::)

Not sure if it's the load or plate tune cap but it looks like a slice of the pi is missing.

a bunch of us headed to the "Glen" one year and got stuck in a massive traffic jam. The road was loaded with trucks. This was the one and only time I was on CB keeping in contact with friends.
I got on 19 and said "this country needs a good rail ststem to get all these stupid trucks off the road" Truckers went crazy.

I don't see any RF connection to either side of the plate choke, so he wins that one.  I will give him the benefit of that doubt that he would have put it in the right place.

My guess is he gave up when he realized that he was running out of space for the power supply.  Not much room for a high voltage filament transformer, filter choke, filter caps and power transformer not to mention, filament transformer for the tube and big bleeder.

js

yeah, I'd've put the rectifier fil. xfor on anyway and enjoyed the purple glow! He had the right idea to impress all his friends.

So it would have been good background for the real amp under the desk.   
"lookee what I built. h'ain't it purty?"

Well, gotta admit in my 'career' I built one once, from surplus ARC5 caps, etc. 6JB6 GG driving a pair of 6LQ6's GG.  Plate tranny came from a Link FM base.  Used dyno tape labels and it was real 'purty' too. Even had the guy's 3x12  ;D CB call on the panel.

I missed out on getting a CB call sign, never had a CB till I could drive, by then it was over.
The old farts that were issued them brag about it. Bunch o' rednecks.