hypothetical 10 meter amp question

[Moleculo]

Booty...beats me. You can see in that second link that the amp has switchable band pass filter built in. That's a good thing. It says the low pass filter is "6m low pass" so that means the cut off is at 50mhz. IMO, it should be 30mhz, but whatever. It's only a 250w amp...almost not worth the trouble to me, but the price is reasonable

The first link doesnt' give a whole lot of info. I'm guessing it's probably a similar amp, but for 110v. That might be useful if you have a QRP rig.

 

[justflyawaynow]

WOW I think I really like you guys... I was expecting to get ripped a new one by bring up my interpretation of part 97. I guess you can say I have not had too many good experiences on forums.

Ok then... The problem with the Ameritron amp is that I want to mess around with something, electronically. That amp is ready to go out of the box. I have seen the Texas star thing before... perhaps I will look a little closer at it.

I like old vintage stuff and/or something a can screw with a bit. I would never in a million years want a brand new mobile HF rig that did 160m to 70cm! Eff that. I like older stuff that feels like it should.

Who knows... maybe a barefoot(sorry for the cb term) 10 meter mobile will be enough for me without an amp.

Anyway.... I am currently looking at TS-520's, when will it ever end?

 

[W5LZ]

justflyawaynow,
To keep you from being disappointed, and to 'live up' to your expectations, here's the 'ripper'.
Most 'CB' amplifiers are junk, just do not have the standards required by other services. Not all of them, but most of them.
Another one of those 'rippers' is that convenience always has a cost. It can be $$$ or it can be quality. If you are interested in 'cheaper', then that's what you get with quality too. If you don't want to 'tune' something, you want it to do it by it's self, expect to pay for that convenience both in $$$ and in complexity. (I like 'twiddling' knobs, so would rather tune than spend, it ain't easy being this cheap you know!)
The amplifying device, tube or transistor, always has limitations. It will tend to work better in certain ranges for frequencies than in others. The 'trick' is to select one that works 'good enough' in the region you want it too. Tubes tend to work 'better' at lower frequencies than transistors, which depends a lot on the particular type tube/transistor, naturally. (Try taking that to the 'electronic' bank and you won't believe the laughter it'll get ! Tends in that direction though.)
If you like 'fiddling' with electronic stuff, the used market is a huge place to find great stuff! Some times you'll get something that doesn't 'require' fixing to make it 'better', but that's a sort of rarity, kind'a. (I just happen to have this 'AL-811', serial number 13. It requires 'fixing'.)
Is there really anything in this that you just couldn't live with out? Nope, just something to think about.
- 'Doc


PS - No, the AL-811 isn't for sale... unless you offer enough. Unfortunately, I don't think you're that silly. RATS!

 

[Beetle]

I have to echo Doc's comments about CB amplifiers in general. They are illegal, first of all. And why should a "manufacturer" of an illegal product be terribly concerned with quality, or cutting a few corners? No reason at all.

I understand your wanting to do something in the field of electronics; however, "improving" a CB amplifier seems somewhat akin to polishing a cowflop.

Just my opinion. Your mileage may vary. Not available in all states. Take as directed. Some restrictions apply. See store for details.

And by the way, the term "barefoot" originated in amateur radio long before CB ever came on the scene.

 

[justflyawaynow]

Thanks for all the info guys.

I have to wait for this HR2150 to come in the mail. $50 was an ok price right? Display has issues... seems easy to fix from what I have read. And it also seems I found a kenwood 520s i was looking for. It needs some work too.

I have to take a trip to VA in a couple months to get a new Army mos. That will take 6 months so it looks like I will have my hands full for now. I will keep an eye out for any "deals" in the amp department. I will steer clear of any cb amps... unless it looks really well built and is a good deal.

73

N9RDK

 

[bob85]

booty, the amps you posted work on hf, they are basically a rm italy cb amp with filters and a few things added, the basic amp is still the same circuit as the cb amps, the negative feedback circuit works the opposite way to what it should in a decent hf amp,
output climbs as you go down in frequency if you dont reduce drive,
a few locals use them, seem work ok but they can break out into self oscillation on certain frequencies and drive levels, some sound better than others right out of the box, overdrive protection does not always work if you accidentally input 100w.

 

[Moleculo]

Justflyawaynow:

I have something you might be interested in playing with. It's a transistor amp that has 4 MRF-454 transistors in it (if I remember correctly!) It was a project I worked on a few years ago to turn it into a 10-80m amp. It was cleaned up quite a bit, and it was working. It had a lot of gain on the lower bands so you really had to be careful about how much power you put into it. Anyway, one day I popped the keying relay in it and never got the urge to fix it. It worked really well on the higher bands. If you're interested, PM me...it would make a real fun project and I'll make a deal on it to move it.

 

[kd4e]

3-amps-for-1 & Worth-More

BTW, a long time ago I emailed the maker of Worth-More Electronics about building me an external band switchable band pass filter and he said he would do it. I don't remember the cost though. Actually, this would be a fun project to build...I just don't have the time to research the details (and I don't really have a need anymore!)

I tried to get one from him years ago as well and could not.

I have three 1200w ss amps (they use eight MRF422's each) from a Danish Marine company called Skanti. One has inadequate 80, 40, 20m filters & they all really needs something like the Worth-More Chebyshev filters.

I got the amps together with two power supplies which provide the necessary 28+vdc. (Two amps are essentially complete in rack mounts, one needs two MRF422's replaced on one board.)

I don't have time for the project & am looking to Trade them all for a Worth-More 1200+, a Henry 750, or some other 12v mobile amp with 600w or more true output & proper filters.

Just in case you hear of someone who is good with ss amps & might like a 3-for-1 trade.

 

[ChrisBama351]

Will an amp but out harmonics with a bandpass filter inline at the radio?
Or does the filter need to be after the amp online going to antenna to stop the harmonics?

 

[fourstringburn]

Generally speaking, clean signal in = clean signal out providing the amp isn't dirty to start with.

Most genuine amateur amps are filtered and usually clean unless hacked up or overdriven.

Those class C and Texas star amps might not be since none of these have an FCC certification and never will because if they are still being made in the USA, they're illegal.

 

[Mudfoot]

Some people use them for CW, FM and data.

 

[tba02]

I use a Cobra XL-450 on 10 meters (4xSD1446) and by all reports it works just fine. Scope shows it is well within requirements.

 

[Tallman]

Generally speaking, clean signal in = clean signal out providing the amp isn't dirty to start with.

The other side of that equation: Garbage in = Garbage out

 

[fourstringburn]

Some people use them for CW, FM and data.

Good point, they would be fine for those modes since a lot of production Amateur amps aren't rated for 100% duty cycle modes.

Of course we Hams can only use them at our station if they were bought used. That's a double standard on the legality issue.

 

[Onelasttime]

An amp does not know if it is being used on 10m or 11m or 12m etc.......Problems are poor input/output tune and lack of filtering on cheap amps. Very few amps even those used by amateurs use low impedance transistor to feed bias to transistors. So with the right knowledge, you could redo input and output tuning and add filtering. Likewise, you can add a separate bias circuit in place of the crude non-temp. tracking sandbar resistors used in most CB amp grey market amps.

You could also just order a modern well designed a very affordable and durable amp from Brian at Telstar Electronics and not worry about all that.

In terms of tube amps if you want modern new construction your choices are very limited unless you build it your self.

If looking at tube amps spend more upfront and get all the power you think you might need in the future if you can afford too. You can buy a legal limit amp and not use all of it's power output. Buy it once and have it for life!