Correction: xcvrs with choice to xmit Class A are, at least, the following:
FT-1000MP Mark V, FT-9000Contest, FT-9000d, and FT-9000MP. The latter three
also have a bias adjustment on the front panel to slide Class A downward away
from pure Class A in SSB or CW modes. I burned up a Mark V by running it full
Class A (only choice on that rig) and at about 40 watts... great techs tried to
fix it and it blew two more sets of finals before I lost track of it. Morale,
do not run a Mark V in Class A. Today, I own K3f, FT-9000d, and IC-7800, as
well as KWM-2A, and several other rigs. Very fun to compare them.GL 73
Charles Harpole
k4vud@hotmail.com
> From: jim.thom@telus.net
> To: crc@cyberlink.bc.ca; amps@contesting.com
> Date: Sat, 18 Aug 2012 00:09:29 -0700
> Subject: [Amps] Re K3
>
>
>
> -----Original Message-----
> From: Fern
> Sent: Friday, August 17, 2012 9:11 PM
> To: Jim Thomson ; amps@contesting.com
> Subject: Re K3
>
> Jim:
> Where in the world are you getting your misinformation from re the K3?
> You don't own one so quit running the darn radio down. Most of us ham don't
> run any more than the legal power of 1500 watts so there's no need for a 200
> watt exciter. I happen to have Icom, Kenwood and Yaesu rigs and by far, the
> K3 has them all beat without a doubt. It would be nice if people would quit
> running down equipment that they don't even own.
>
> ### good info Fern. Tell you what I will do. I will buy one next
> week....with the
> provisio if I don't like it, I can get a full refund for it. I'm getting
> tired of one flop after
> another after another for every xcvr that comes out. I have yet to own any
> of em, that work right,
> designed right... outa the box.
>
> ## since u have all the fancy test gear, do us all a favour and measure the
> 2 tone TX imd at
> 120 w pep out, ( or what ever max power on ssb is), and do it on all bands,
> including warc.
> Do it the correct way, not the arrl fubar method either. IE: db below one
> tone of a 2 tone signal.
> Then give us the results for imd 3-5-7-9-11-13.
>
> ## while you are at it, measure the RX audio THD and max po of the k3's
> audio section.
>
>
>
> I've been in the
> communications business for over 50 years with owning my own business for
> over 25 years so I think that I have a bit of an idea as to what I'm
> talking about as I have on my disposal all of the test equipment to check
> this all out.
> The output power on the K3 is just over 120 watts dc (key down on mine)
> not 100 W pep as you stated. 99% of legal hf amplifiers don't require any
> more than 100 watts to drive them to full 1500 W allowed power. No offense
> Jim, I'm just stating the facts.
> Fern
>
> ### allowed power is 2250 w pep... AFTER feed line loss. IE: measured at
> the ant
> feed point. With just .5 db loss= 11% loss, the amp has to put out 2528 w,
> just to get
> 2250 w pep at the feedpoint. 1db loss = 21% loss. Now we require 2850 w
> out.... to
> get 2250w at the ant.
>
> ## I only have one grid driven amp here, (its being sold),
> the rest are GG. The hb 3x3 will do 2.5 kw pep out with real low
> IMD..with just 100 w
> pep drive. But that is a moot point if the xcvr is not up to snuff. The
> arrl lab tested
> the k3 at -29 db pep for IMD3. That's -23 db below one tone of a 2 tone
> signal.
> That doesn't meet any standard, ITU, mine, or anybody else's.
>
> ## what's the point of me having an amp capable of -59 db pep for IMD3....
> if I don't
> have the mating clean xcvr to drive it with.
>
> ## fact is, a 55 year old KWM2 will eat the k3 for breakfast, as far as
> TX imd.
> Your typ 200w SS xcvr, when run at 100-120w pep out, is fairly clean. The
> only class A
> 100 w pep out xcvr out there is the yaesu 400w version of the 9000. And
> even that xcvr
> has enough problems.
>
> ## BTW, can you put the K3's sub rx on a different band than the main RX.
>
> Jim VE7RF
>
>
>
>
>
> ----- Original Message -----
> From: "Jim Thomson" <jim.thom@telus.net>
> To: <amps@contesting.com>
> Sent: Friday, August 17, 2012 7:57 PM
> Subject: [Amps] K3 spike problem
>
>
> > Date: Thu, 16 Aug 2012 14:11:02 -0700
> > From: Jim Brown <jim@audiosystemsgroup.com>
> > Subject: Re: [Amps] K3 spike problem
> >
> > On 8/16/2012 5:59 AM, Joe Subich, W4TV wrote:
> >> In addition, if Charlie is using external ALC (he does not say) and
> >> has the K3's power control set too high, he will see the spike due
> >> to ALC time constants*in the amplifier*.
> >
> > It should be noted that when high quality rigs like the K3 are used to
> > drive a power amp, amplifier output power should be set by using just
> > enough drive power, NOT by setting drive power higher and using ALC to
> > reduce it. For at least 30 years, Ten Tec has recommended AGAINST using
> > ALC with their rigs and power amps in this manner. The only good reason
> > for using ALC between a power amp and a transceiver is to protect the
> > amp in case of a failure in the antenna system.
> >
> > ### Unless the amp has a front panel adjustable ALC control knob,
> > it won't work anyway. Also, the alc time constant in the amp HAS
> > to match the alc time constant in the XCVR..and NONE of em do..
> > so don't waste your time.
> >
> >
> >
> >
> > In an excellent applications note on the topic, Tom, W8JI, noted that
> > many rigs produce a spike of their full power output when their drive
> > level is set well below full power. For those rigs Tom recommends a
> > passive attenuator between the rig and the amplifier. The K3 is NOT one
> > of those rigs -- indeed, it is quite well behaved. It's also one of the
> > cleanest rigs on the air.
> >
> > ### IOW, if the amp requires 50 watts of drive, then use a 3 db pad
> > between
> > the xcvr and amp, then run the xcvr at 100 w output. IE: the pad is used
> > to
> > control the power output, and not any control in the amp. If 25w drive
> > required,
> > then a 6db pad is required. Any pad is a PITA. The 3db pad has to be
> > rated
> > for at least 50 w CCS. The 6 db pad has to be rated for at least 75
> > watts CCS.
> > Then you also lose 3-6db on RX... which is the last thing you want.
> >
> > ## a simpler approach to adjustable po is to just put -9vdc across a 50
> > k
> > pot...then feed 0-9 vdc (neg) into the alc buss on the xcvr. Crank po
> > control on xcvr to max... then adjust pot for desired output..from 0-max.
> > No alc time constants to mess with, since you have already developed the
> > alc voltage with your -9vdc source. And no spike problem.
> >
> >
> >
> > ## The K3 is NOT a clean xcvr on ssb. It has typ lousy imd... like -29
> > db pep
> > for IMD3. That's on a par with sweep tubes from the 70's. It only does
> > 100 w
> > pep out, and I require a 200-250w pep put xcvr..so no K3 on my desk.
> > Ten tec needs to go back to the drawing board, and
> > build a competitive xcvr.... not one that's suited for cw only + grid
> > driven
> > tetrodes.
> >
> > Jim VE7RF
> >
> > 73, Jim K9YC
> >
> > _______________________________________________
> >
>
> π
>
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