Amplifier input and output

Hi guys, hopefully this hasn't been done to death, I have searched but can't find an answer.

I am looking at picking up the kl203p amp, I notice the power specs say 1-10 watts input and 100 watts max output, am I right in assuming that a standard 4 watt output will only give me 40 watts output of the maximum 100 watts?

To be honest I can see 40 watts being enough, I am getting lots of long distance contacts on my unmodified crt6900 (I got from South Wales to the west Indies recently on an S7 on the usb, very pleased with that.

Incase I didn't say watts enough times, watts watts watts.

Depends on the pills that are in it, i run a Mirage M75 with two matched Toshiba 455's, 2 and a half watts into it and a 100 watts PEP out of it, my other amp has two matched Toshiba 454's in it, 4 watts into it and 160 watts PEP out of it, so it depends on what pills are in it.

Hi Mike,

If only it were that simple.

You'll get a massive increase in output power driving them with as little as two Watts and probably won't gain much more by driving them harder except adding to their eventual demise. (Maybe why they sell so many of them but often blamed on poor design or output transistors before becoming the next generation of land-fill or ebay 'bargains'!)

Obviously others will contest that and depends on what measuring equipment (or lack thereof) utilised to check their performance.

With a 100% duty cycle transmission mode such as CW or even FM and the most basic of power meters you'll see the almost true power output of such devices. When running SSB or single side band modes unless you have a true PEP or peak-envelope-power meter you'll see much less no matter how loudly you whistle or scream 'Hola'.

It's often the 'whistle-up' or quest for a higher power meter readings that drive people on as well as add to the eventual destruction of such devices.

In the end it's up to you whether you feel that you'd benefit from adding them onto your setup and most would state that they do. Especially if they've added them and managed to hit a good bit of 'skip' that we've been experiencing during this solar cycle. (Or hit their mate up the road at +30.)

Currently we've had conditions where simple low power rigs and small antennas are giving great DX contacts as many members here can attest to. Always remember that no matter how many more 'Watts' you add to your output it doesn't help what you receive.

I'll probably get a lot of flack for the above comments (as ever ) but when you hear the "Wun-Keelo-Watt" stations and find out you can't get back to them, increasing your power may not always help. More power can make your transmission go further for sure but you don't want to be the 'alligator' station where you're all mouth and no ears cluttering the airwaves with incessant shouting.

It's your money Mike and only you can see fit on what to spend it on. You'll definitely get "More Watts Igor!" with them and see if it makes a big difference or not. (They're cheap enough nowadays to give it a punt.)

Sorry there's no 'Bird Meter' mention, fancy maths, graphs, spreadsheets or even pretty pictures of coloured anodised aluminium fins.


All the best,
Victor



(Remember that all opinions expressed or what some might call 'nonsense' is merely my own thoughts and not attributed to the Charlie Tango group as a whole. Slag me off if you'd like but don't sully the group as a whole.)

Again, amazing advice Victor, thanks. I'll pick one up and see how it goes.

Revo Mikey wrote:

...

I am looking at picking up the kl203p amp, I notice the power specs say 1-10 watts input and 100 watts max output, am I right in assuming that a standard 4 watt output will only give me 40 watts output of the maximum 100 watts?

To be honest I can see 40 watts being enough, I am getting lots of long distance contacts on my unmodified crt6900 (I got from South Wales to the west Indies recently on an S7 on the usb, very pleased with that.

...

That looks about right, ten times out what goes in, that's my experience. I've had a few of these amps, still got a couple, but their ssb performance is less than steller. They're great on FM, 40W out makes a hell of a difference from 4W even locally, especially as most people have a lot of interference. They do get very hot though so a fan is needed as they power fade when hot, I'm in the middle of fitting a temp switched fan to one of mine.

SSB performance is poor though imho, they aren't true 'linear' amps and tend to distort the audio on sideband making it less readable which is a shame. I've found 30W of clean clear SSB straight out of the radio is better than 100W+ of poor quality sound. By the same token 15-20W on FM barefoot is as good as 40W from an amp, so if your radio is high powered export version I don't honestly think you'll be any better off, but that's just my opinion.

Personally, I think valve (tube) amps work a whole lot better on SSB and appear to have a much cleaner output too so might be a better choice, but whatever you get make sure you don't overdrive it. If you're going to get an amp why not go big, 2-300W+ is better than 20 or 30W and will do a good job if it's clean, put some real 'fire up the wire' lol.

Thanks Mitch, great info.

I do have an update, I realised my crt6900 was the new model, it actually has 40w output on FM, I didn't even realise, if id wired that into the amp it would have likely made short work of it.

I tested this by connecting my Swr Meter with pwr checker, it pinged off the scale on pwr fwd. Even on minimum it was thrusting about 2w out there.

Doesn't seem like much point installing an amp on that really. 

I learnt a lot from this thread though so thanks again fellas