EMRFD Message Archive 1963
Message Date From Subject 1963 2008-08-17 18:38:03 Jim Miller Approaches for low voltage transmitters? If you don't have 12v supply how do you achieve 5w CW?
Anyone have links to transmitters with reduced supply voltages?
1964 2008-08-18 09:31:56 Kenneth Stringham Approaches for low voltage transmitters? You don't need 12v supply to achieve 5w of output. You just need to modify the design to use lower voltages.
The PA output impedance for the matching circuit would be changed from 14.4 ohms to 2.5 ohms for operating @ 5v. You would provide appropriate lower levels stages to achieve the necessary drive power to make it work.
Ken - AE1X
1967 2008-08-18 12:44:43 ehydra Re: Approaches for low voltage transmitters? You mean on a 50 ohms antenna? Go with a low-output-impedance stage and
an impedance transformer.
Jim Miller schrieb:
> If you don't have 12v supply how do you achieve 5w CW?--
> Anyone have links to transmitters with reduced supply voltages?
> jim ab3cv
> Yahoo! Groups Links
1969 2008-08-18 12:44:53 wimmie262000 Re: Approaches for low voltage transmitters? 1970 2008-08-18 13:43:18 Johan H. Bodin Re: Approaches for low voltage transmitters? Joop wrote:
> For single band CW operation you might like to consider a Class-E PA.The above paper is really good but it assumes an almost infinite DC feeding
> Have a look here:
inductance. The following paper takes a look at class E operation with more
practical values for the DC feeding RFC:
As you can see, it is possible to run class E with quite a small RFC but the RF
ripple current in the DC feed will be larger so good decoupling on the DC side
of the choke is important.