[AMRadio] Are we doomed?

[w5jo at brightok.net]

No argument taken here Rob and a valid observation.  I have not experienced 
the problem you mention.

I have made long transmissions that any normal ham will do  on the band, but 
I have not made a 30 minute continuous transmission so can't speak to that. 
But under normal circumstances it has not had one problem in that area.

I utilize an LP-100A wattmeter at the shack and it does not change even when 
I have engaged in an hour long +  QSO with Don, K4KYV on 160 or 80 and have 
done both.  My inverted L shows, at the transmitter end of the long feed 
line, about 1.9 : 1 without the tuner and that is at 1.920 MC.  I believe 
that if the mismatch was going to occur it would have shown in my 
application.  If anyone is seeing that kind of problem they may be using 
more power than the unit can stand or have mismatch problems at the antenna.

I am a bit dismayed that the guy (John) who was technical support at MFJ may 
be gone as Charlie mentioned.  He was knowledgeable and would not have made 
that kind of statement.  I spoke to him about the 998RT before buying and he 
indicated that it would handle 500 watts carrier for at least 10-20 minutes 
duty cycle and all their tuners would be about half power in any continuous 
mode.  They understand that they will be used in RTTY and digital modes 
which are very near what AM does.

of course you mileage may vary since none of us will have the same type of 
installation.

73,

Jim


-----Original Message----- 


Hi Jim; I don't want to get into an argument as I am certain you speak
of honest experience.  However, like many folks in continuous duty
modes, you left out one key bit of information:  transmission time.
If you have no trouble with the tuner after a 30 minute transmission
then I stand corrected.  But I have a hunch you'll see impedance match
creep at about the 15 minute mark if not sooner at 350 watts carrier.

73
Rob
K5UJ

On Sat, Apr 25, 2020 at 2:08 PM <w5jo at brightok.net> wrote:
>
> Charlie and group,
>
> I bought an MFJ 998RT about 8 years back and installed it at the base of 
> my
> tower.  It is hooked to my coax which is then routed to an antenna switch
> then to a Inverted L for 160 and 60 meters and my common 80/40 meter
> dipoles.
>
> I use it with my GK 500 and my AL 1200 both without a bit of trouble 
> across
> the bands and it tunes fine.   It has withstood the test of time and
> survived numerous thunderstorms without damage but occasionally the memory
> scrambles so have to reprogram the frequency memory by transmitting into 
> it.
> I have not had one problem with it using the GK 500 which puts about 350 
> or
> so watts to the unit and it modulates to 1200 to 1500 watts on 3.870-90
> meters where my antenna is cut for 3.750.
>
> I have no trouble recommending it.  Their stuff is better built today than
> in years past but if you friend is interested I would suggest it for any
> level below 300-400 watts AM carrier.  I don 't have any experience with 
> the
> smaller units so can't speak to them.
>
> Jim
> W5JO
>