Hello Mal,
On Sunday, November 27, 2016 you replied to my thread.
Thanks for the replies everyone, I will try a low power Class E amp to
learn more about this class of amplifier. On the cards for 2017 is go
at an H bridge amp, too, I have much to learn and I thank you for all
for your patient help.
Best regards,
Chris 2E0ILY mailto:[email protected]
My part time LF grabber is at http://www.chriswilson.tv/grabber.html
> John
> I always used SQUARE WAVE to drive my class D es E amps. The Decca 5501
> modules input is Sine or Sq wave, the input cct shapes the sine wave to Sq
> de mal/g3kev
> -----Original Message-----
> From: John Rabson
> Sent: Sunday, November 27, 2016 10:28 AM
> To: [email protected]
> Subject: Re: LF: H Bridge power MOSFET based amps question
> My experiences with class E single ended amplifiers is similar to that
> reported by Mal. The only caveat I would add is that you should be quite
> sure that you have the right driving waveform. During my early experiments
> with a design based on G3NYK’s spreadsheet I tried a sine wave rather than
> the square wave it should have had. The result was lower efficiency and a
> short life for the FET.
> John F5VLF
>> On 26 Nov 2016, at 11:35, mal hamilton <[email protected]> wrote:
>>
>> Chris
>> The Decca 5501 amp modules use a H bridge class D configuration followed
>> by a series resonant PA circuit and this is probably one of the most
>> reliable amplifiers about. Use suitable rated FET'S to give the desired RF
>> output.
>> Also the protection cct used avoids disaster in the event of an antenna
>> failure short/open cct,
>> I have built lots of class D 1Kw push pull amps over the years for LF/MF
>> but they are vunerable to damage with load variations whereas the Decca
>> bridge amps survive. I never had a failure with the Decca, and have been
>> using them for many years.
>> Another approach which is worth a consideration is the class E amp single
>> ended, these are very reliable and avoids the crossover switching problems
>> with the push pull system. Setting up procedure is critical but there
>> after very stable,
>> Hope these observations help you
|
