Hy-Gain Afterburner (linear CB amplifer).   How to test? - Page 1
Forum section: electronics / projects

author: gooseEL34
author_rank: Regular Contributor
timestamp: April 11, 2015, 08:26:40 pm
content: Hey all-I cruise the goodwills and thrifts for metal project boxes and other items that I can scavenge for making guitar pedals, preamps, amps, etc.I came across a Hy-Gain Afterburner Model 404 Linear Amplifier. I believe it is an inline signal amp to be used in an auto, truck or boat (based on the input being 12vDC via screw terminals (which would be right for US Car batteries).Bottom line is this.... Some of these sell on ebay for $50 and up, and even though I was going to gut it and use the metal project box and switches for a guitar effects pedal, I might be better off to sell it off and buy parts with the money.The question is this....I cannot seem to find a schematic or manual online anywhere. It has three switches and two audio connectors. The switches are rocker switches and are labeled ON/OFF, SSB/AM-FM, and XMT/STANDBY. There are two pots labeled LOAD and TUNE.The audio connectors appear to be CB radio thread on connectors.The back panel indicates it is for 6 meter (50-54 mHz) and 10 meter (28-29.7 MHz) applications (which I believe are CB or Ham radio designations).So gurus....I have no ham setup nor CB....Can I test this thing with a signal generator, scope and/or Fluke?I have a HP206 sine generator....Thanks

author: SeanB
author_rank: Super Contributor
timestamp: April 12, 2015, 08:05:55 am
content: Audio connectors, no.......... PL259 connectors yes, used for RF power in and out. This is a 50ohm input and output amplifier, so you will need to test it with a 50R dummy load on the output, or you **__WILL__** blow it up within milliseconds if you turn on the output stage.With that out the way, you need a 12V car battery ( or a 12V power supply capable of delivering 50A or so), and place a 300W dummy load of 50R to the output using some PL259 connectors and coax cable ( RF cable, not the wimpy stuff used for audio, this has to handle up to 400VAC and 10A of RF current) and feed the input with a 29MHz signal, at a level of around 5W, which is a little beyond what the 206 can generate. Then apply 12V to transmit line and see the power supply is showing you suddenly are drawing 20A plus, and the dummy load is getting warm as well. Basic function test then passed.

author: Stonent
author_rank: Super Contributor
timestamp: April 12, 2015, 08:07:41 am
content: Just be careful if you ever try to use it for its intended purpose, in some places linear amplifiers on CB radios are illegal.

author: Rufus
author_rank: Super Contributor
timestamp: April 12, 2015, 04:45:59 pm
content: Quote from: gooseEL34 on April 11, 2015, 08:26:40 pmThat thing is almost antique. Of more interest to Hams than CBers. If it isn't in terrible condition I suspect you could find someone who would like to own it and you won't find much in the way of useful components inside.

author: gooseEL34
author_rank: Regular Contributor
timestamp: April 17, 2015, 07:30:04 pm
content: Rufus.Thanks for the opinion. I probably will offer it to my HAM buddy (local District Attorney) and see. So what was the function of this thing? Was it to boost a CB/HAM signal?Looks like it has a tube inside it.Am I correct in that it was probably designed for a car/truck? (having post terminals for the DC supply (car or truck battery))?

author: Rufus
author_rank: Super Contributor
timestamp: April 17, 2015, 08:23:39 pm
content: Quote from: gooseEL34 on April 17, 2015, 07:30:04 pmYes it is a power amplifier for 10 and 6m ham bands for mobile/portable use powered from 12v dc. Yes it has a pair of valves (because it is ancient) and needs a DC-DC converter for them which is what the big transistors on the back will be doing. It was probably made in the 1960's.

author: calexanian
author_rank: Super Contributor
timestamp: April 18, 2015, 04:44:04 am
content: Those are noisy dreadful sweep tube amps. Do everybody a favor and turn it into something else.