Search results

I remember a video that was posted here that showed the person behind AMPOWER amps "touting" their merchandise. Based on the nearly incoherent babble in that video I woudn't buy a single thing that guy makes, regardless of whether it's an amplifier or scrambled eggs.

You'll need 2 matched pairs or better yet a matched quad. Item SD1446-MP is available from rfparts for$79.90. It consists of a matched pair, and SD1446-MQ is a matched quad for $159.80. Here's the link: PT - SD - TIP Transistors at RF Parts Company

GREAT post. I've got a few server supplies at home right now.. they work great! You won't find many cheaper sources of clean amperage.. server supplies are specifically designed for extreme regulation and very high reliability.

To add to the above post, I had an interesting experience and discovered a major improvement while building this set of low-pass filters from CCI. Some of the following plots and circuits were posted in the OP, but they are most relevant here. In the base configuration (5-pole) the input...

Here's a writeup I did a few weeks back detailing the construction of a low-pass filter kit for 80m. The same basic process applies to any HF/VHF band. The complete kit for all 6 filters (160m-10m) can be purchased quite reasonably from Communication Concepts here. This is just in case anyone...

That's absolutely true. Some of today's MOSFET technology is simply incredible. It's possible today to obtain up to 1.25kW from 1.8-600MHz from a single device that costs about $250-300. Crazy stuff really when you think about how things were just a few years ago. Hell, these here will do 1kW...

I have an 800VA IsoBox medical grade isolation transformer system, a working pull from medical equipment. Transformer from Toroid Corporation of Maryland. Provides 8 outlets at 110VAC plus 5VDC and +-15VDC sources. Good for isolating equipment from the mains for protection and noise reduction...

Well that will have been already decided in the not so distant future: As you can see, DMC will be revived very soon and re-release it's early 1980s design, but will add the oh-so-popular Mr. Fusion as standard equipment. Their future director of propulsion research, Dr. Emmett Lathrop "Doc"...

Also, to add further, if you look at the picture you can see that there is a spot for another amplifier stage, with a cutout for the transistor clearly visible. In a slightly different model of this amplifier a drive stage is added to boost the gain. 5-15W in gives 120 out.

You do have a good point, but it's not quite so bad as to say "why bother". increasing the power output from 40 to 120W is still a noticeable increase. While math does help visualize what the difference will be, it doesn't always take the lay of the land and the antenna's height (or lack...

One reply I have is that it's really not just as simple as adding band-selectable filters (which is what I assume you meant by "auto-tuner board"). While I'm an advocate of doing exactly what you suggest, having built a couple sets of filters to use with CB-style amps, it doesn't equate to the...

You know, this forum has given to me in that it counts as a major resource that I've used to learn. There are people here who know far more than I about this stuff, and often they've been kind enough to help me learn. Now I'm just trying to put information that I find fascinating out there so...

Nice Audioshockwav! I didn't mention the fact that many transistors have built-in matching, but IIRC that's strictly a BJT thing since MOSFETs have higher impedances by nature.

When the amplifier is intended to be used at such a narrow bandwidth, such as the single-band VHF/UHF amps in the pics, it's not necessary to use matching transformers. The kinds of transformers found in CB and HF amplifiers provide broadband matching, which means they match impedance across a...

Just realized I had a couple amps here that show what we're discussing so I took a couple pics and labeled some key parts: This is a 136-174 MHz class C FM-only commercial/public safety amplifier that is frequently found on the ham bands. It uses 3 single-ended stages: Here's a class C UHF...

Depends on the configuration. You might have push-pull, or you might have 2 single-ended stages in parallel. There are differences in configuration between the two and in their respective spectral outputs, and a good description of parallel stages can be found in section 3.4.2 on page 31 in...

I would agree with your thoughts concerning class C sine waveforms. The filters do filter out distortion, resulting in a cleaner waveform. There will still be more distortion than other classes, but simply filtering the output helps a bunch in that department.

A single transistor would make up a single-ended amplifier stage.

Agreed, and thanks.. I hadn't actually seen that the classes had already been discussed at length here, but really it's sort of common sense that it would have been lol. It is "The Worldwide Radio Forum" after all.. Describing the classes was sort of linked to the topic, which is dealing with...

You've already got a pretty good understanding it seems, as you're pretty much right on with most of your speculation. With class B and AB amplifiers it is pretty much standard operating procedure to use push-pull pairs, but with class C it's actually rare outside of CB amp setups. Most class C...