Linear Amp Help

[sdeeter19555]

Nope...

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[elk2370bruce]

Nope the rules habve not changed. All that has changed here is another total newbie is gonna fry himself, his rig, the amp, or the whole damned vehicle electrical system.What's next? mods for the freeband upgrade?

 

[Fanggallo]

Quite funny you say that as I never stated I was planning on hooking this up. Seems you have misplaced the term "newbie" with "assumptions."

 

[n9mxq]

Nope the rules habve not changed. All that has changed here is another total newbie is gonna fry himself, his rig, the amp, or the whole damned vehicle electrical system.What's next? mods for the freeband upgrade?

Well, at least he's here asking questions first. We can at least steer him in a direction that won't fry everything if he hooks it up. I'd rather help him be safe. What he does with the knowledge is up to him.

And yes, they aren't legal on 11 meters.. I'm pretty sure he knows that (and knew BEFORE he started the thread).. That horse has been beaten to death more times than I can count.

 

[ve3fnd]

i see four 2SC2879 - Toshiba Transistors, specs are 2-30mhz and 100watts PEP and i see a driver so its a low drive amp no more than 3 - 4 watts am and id say maby 10max on ssb in. Looks like not a bad lil amp should do at least 300 to 400 watts on ssb and less on am maby 200 on am. as far as i can tell should do more bands than just 10 to 12 depending on how its put together but the 2SC2879's can do all of the shortwave band.

 

[KD9KSO]

In order to not jump the gun, I'd like to get some order in what I am trying to do. With that being said, the question is: How do I "ready" my CB to be used with a linear? My CB is a Cobra 29 Chrome Edition with a Road Devil mic, Wilson 1000 and a 102" whip.

My set-up work great, but would should I do if I'm ready for an amp? Should I turn the CB output down to 4w or something? (I believe it's around 10 watts)

I heard I should switch mics being as the road devil is already adding a lot of power.

Any info on how I should "ready" or "modify" my set-up for a pill would be great.

Thanks.

What else can we infer except that you are going to use it?

Do what you want. I'm not the FCC. But they'll find you.

 

[K7MEM]

Quite funny you say that as I never stated I was planning on hooking this up. Seems you have misplaced the term "newbie" with "assumptions."

There is nothing wrong with being a "newbie". We were all newbies at one time.

In your original post you stated that you already applied power and asked how you check the power output. In another post you asked if a DVM could be used to check the output. Together, it is an indication that you are not going to use it as a paper weight and plan to hook it up. So you are a "newbie".

As others may have stated, to test the output power you need a power supply that is capable of outputting 12 Volts at 60 Amps, an RF source between 1-5 Watts, a power meter, and a dummy load that can handle the full output power.

The design of the amplifier is based on the classic broadband designs that were published by Motorola in Application Notes in their RF Devices Data Book from the 80's. Those designs were really meant only as a starting point for more elaborate designs. The App Notes listed below are a good example. They are lower power designs, but it gets the idea across. They are good reads and will help you understand what the designs are based on.

www.k7mem.com/manuals/AN-779.pdf
www.k7mem.com/manuals/AN-593.pdf

But many manufacturers took these initial designs and started making amplifiers. And, why not. The application notes provided everything they needed to know, including the PDB design. Usually they eliminated pesky things like effective bias for linear SSB operation and output filtering. The output filtering is to eliminate the fifth harmonic products. There is often a switch that selects AM/SSB, but that does nothing to the bias. All it does is add some extra time to the transmit sensing switch, so you don't go out of transmit every time you pause for a few seconds.

You will even see these designs in older Amateur Radio Handbooks. However, they do stress bias and output filtering.

Are these amps used? Yes, by CBers and by licensed amateur operators, who should know better. I have seen bios on QRZ.com where they brag about using these amps, with no modifications.

But they can be made legal, at least for use by a license amateur operator. Amateur radio operators are allowed to built their own transmitters, receivers, and amplifiers. So if you treat the illegal amp as a part and then add bias for AB2 operation, add an output filter, and eliminate that automatic transmit sensing, the amp is legal to use on the amateur bands. Adding proper bias will probably reduce the efficiency of the amp and lower the output power, but that shouldn't be an issue.

I have a amp that is labeled as a Pride-150. But the same design goes by several different names. I bought it at a ham fest for $15. However, I modified mine so that it is legal to use on 10 Meters with my HTX-100.

 

[elk2370bruce]

Quite funny you say that as I never stated I was planning on hooking this up. Seems you have misplaced the term "newbie" with "assumptions."

From your original post, my comments were based on your statenments, not on assumptions. As stated by another poster, it was clear that you were not going use this as a paperweight nor were you aware of the methods of ensuring safe operation that an experienced operator would already be aware of.

 

[Fanggallo]

Well as far as I know, finding out how to properly test a piece of equipment and to see if it is still useable does not imply it is going into my mobile station for hook-up. If need be stated, I plan to sell/give it away.

Thanks to everyone for all the great information. Helped a lot!

 

[Fanggallo]

i see four 2SC2879 - Toshiba Transistors, specs are 2-30mhz and 100watts PEP and i see a driver so its a low drive amp no more than 3 - 4 watts am and id say maby 10max on ssb in. Looks like not a bad lil amp should do at least 300 to 400 watts on ssb and less on am maby 200 on am. as far as i can tell should do more bands than just 10 to 12 depending on how its put together but the 2SC2879's can do all of the shortwave band.

Theoretically speaking, what specifications, (based on the information you provided about this amp,) would I need to power this linear by CB? What would have to be adjusted on the CB?

(I do not intend on using it for myself, just thought I'd expand my knowledge beyond the simple CB setups.)

Thanks.

 

[jdobbs2001]

Wow the quality of the internals

 

[teufler]

don't think so, but then again, what rules are there in the CB band? I think what rules is the biggest and widest signal wins.