don't forget, the 590 takes power and swr readings pre-internal tuner, and 
the tw1 takes them post internal tuner...weather you have the internal tuner 
on or off, this probably accounts for some of the discrepancy.
The tw1 is also a more sensative instrument than whatever the radio uses 
inside, so RF, capacitence and that kind of thing will effect it's power and 
swr readings much more so than the internal measurements.

Like Butch, I would tend to believe the tw1 before any internal measurements 
for the reasons he mentioned.

73
Colin, V A6BKX
----- Original Message ----- 
From: "Tom Behler" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, December 13, 2012 4:57 AM
Subject: Accuracy of TW1 Talking SWR/Watt Meter


> Hey, all.
>
> As I have addressed my most recent issue with the TS590 DC power cable, I
> have noticed something interesting with my TW1 swr/watt meter.
>
> Actually, I thought I already knew this, but my most recent readings have
> reminded me of the issue.
>
> Now, with both of my TS590 power cables, when the rig is set to 100 watts
> output, I consistently get 100 watts as a power reading on the TS590's
> internal meter.
>
> However, when using the LDG TW1 talking watt meter, my readings can vary
> anywhere from 85 to 91 watts, with occasional dips as low as 81 watts.
>
> Keep in mind that all of these readings are taken on a resonant frequency
> with my Alpha Delta DXCC antenna and an SWR of 1.0 to 1.  Also, I get the
> same reading variations with the TW1 when using a dummy load.
>
> I checked the TW1 manual, and they clame an accuracy of plus or minus 5
> percent on 14 mhz, but I think that is debatable.
>
> On the other hand, do we know how accurate the TS590's power meter is as
> well?
>
> I'm not one to quibble over 10 or 15 watts, but I find the inconsistent
> readings with the TW1 to be at least interesting.
>
> 73 from Tom Behler: KB8TYJ