[Lowfer] 1 watt in class & quot; AB & quot; into 32 Ohm load, BW - 600 KHz, and it's an audio amp

[Paul Daulton]

Jay it has been my impression that PM and FM were the same thing. 
Shifting the phase alters the frequency in time domain. A single 1000hz 
tone like PSK-31 into a ssb generator comes out as a single carrier 
1000 away from the carrier freq. There is no amplitude shift so why 
cant psk or its variants be amplified by class C or other classes? I 
realize the psk signal must be generated by either phasing or filtering 
but once generated does it require a linear amp chain to bring it up to 
power?

Only rigs I ever had that ran PM were the Elmac mobile rig and the 
Central Electronics 10B but I never used either in that function. 

Interesting thread, its got me thinking. Can you give any references in 
older handbooks?

Paul k5wms

Quoting jrusgrove at comcast.net:
> Andy
>
> PSK, BPSK, QPSK, WOLF generally require a linear amplifier although at least
> several lowfer stations
> have run some of those modes through non linear amplifiers with no problems. 
> There's little chance
> that a PW 1-watt lowfer is going to cause intereference - especially if run
> outside of the watering
> hole window as is customary when transmitting a 'digital' mode. 
>
> RTTY, Pactor, Jason, Amtor, MFSK, Olivia, Domino, Throb, WSJT, WSPR do not
> require a linear
> amplifier and can be run through your existing lowfer 'Class D' final with no
> concerns. 
>
> Jay
>
>
> ----- Original Message -----
> From: "Andy - KU4XR" <ku4xr at yahoo.com>
> To: " European & UK) and MedFer bandsDiscussion of the Lowfer (US"
> <lowfer at mailman.qth.net>
> Sent: Thursday, November 25, 2010 5:20 PM
> Subject: Re: [Lowfer] 1 watt in class " AB "into 32 Ohm load, BW - 600
> KHz, and it's an
> audio amp
>
>
> > --- On Thu, 11/25/10, JD <listread at oswegoblade.com> wrote:
> >
> >>
> >> We also need to bear in mind that Andy was asking about
> >> Part 15 operation, which is limited to 1 watt DC INPUT. 
> >> The efficiency of Classes A and AB are pretty poor,
> >> and B is barely adequate. 
> >>_________________________________________________________________
> >
> >
> > Hi JD:
> >
> > I suppose that this fact is probably one of the biggest reasons
> > that there are not many lowFERs sending linear modes on 1750 meters. 
> > 70% efficiency would be excellent performance in a Class " AB " amp. 
> > Unless I'm mistaken, I think the distortion in a Class " B " amp
> > might be a little too high, but on the other hand; at LF would it
> > even be noticable ?? Possibly so if it distorted the transmitted
> > waveform of a digital mode enough that decoding it would be difficult,
> > or impossible. I don't have enough experience to know. 
> > I did build an HF to LF Transverter using a SA612, and a TDA7052B. 
> > The IF was at 28 MHz, and I was trying to use an old Radio Shack HTX-100
> > 10 meter mobile as the tunable IF. It works, but the drift in the old
> > radio is excessive, so not very useful. Antenna current readings with
> > the QRSS Class " D " setup on the old antenna were 180 Milliamps, and
> > on the Linear Transverter set for 1 watt DC Input on the TDA7052B audio
> > amp, the Antenna current was 110 Milliamps. So there is certainly a
> > drop in output efficiency with any Linear system. 
> > I do still have the desire to get a Linear PA going at some time, and
> > run something in addition to the QRSS signals on the band. Probably
> > just need to change the crystal in the transverter, and use another
> > radio as the tunable IF. I guess that's the most logical route to take. 
> >
> > 73:
> >
> >
> > Andy - KU4XR - EM75xr - Friendsville, TN. USA
> >
> >
> >
> >
> >
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Paul Daulton K5WMS
beacon WMS 185.302 khz qrss30/slow 24/7
Jacksonville,Ar 72076
em34wu