[Elecraft] W1 - no autoscaling

[David Yarnes]

Glenn,

I'd drop a note to Gary at Elecraft support.  I bet he can give you some 
good pointers to check out pretty quickly.  If you have checked your 
connections carefully, I'd say it's probably that some part of the PIC, or 
one of the other IC's, got zapped.  It's a great little kit.  I love mine, 
and it seems to be very accurate.

Dave W7AQK
----- Original Message ----- 
From: "ON4WIX" <on4wix at skynet.be>
To: <elecraft at mailman.qth.net>
Sent: Monday, May 26, 2008 10:32 AM
Subject: Fw: [Elecraft] W1 - no autoscaling


> Hi again,
>
> I have some more findings that may help in narrowing down the cause of my 
> problem:
>
> It seems like the W1 recognises that more power than 1,4W is being sensed 
> but somehow it does not react as it
> should, i.e. autoscale up to a higher power level. It just reads full 
> scale when I run more than 1,4W and the display takes a long time to 
> recover at key-up (+/- 1 second before the FWD PWR leds start to switch 
> off).
> I have also tested the W1 running on a 9V battery and I get the very same
> results.
> Furthermore, with the W1 hooked up to my PC running the Elecraft W1 
> software
> v1.10 I get accurate power readings up to 15 watts. Anything above 15 
> watts
> is displayed as 15 watts, period.
> I checked all components around the U4 scaling section and everything 
> seems fine there.
> Is it possible that the PIC in this kit is corrupt? I do get accurate 
> on-board readings up to 1,4 watts and
> the software shows accurate readings up to 15 watts so the problem seems 
> so
> be firmware-oriented rather than a hardware problem.
>
> Any input would be very much appreciated.
>
> 73
> Glenn ON4WIX
>
>
> ----- Original Message ----- 
> From: "ON4WIX" <on4wix at skynet.be>
> To: <elecraft at mailman.qth.net>
> Sent: Sunday, May 25, 2008 5:57 PM
> Subject: [Elecraft] W1 - no autoscaling
>
>
>> Hi all
>>
>> I just finished building the W1 wattmeter kit. All went fine without any 
>> problems.
>> The part "Checkout and Calibration" (p9 of the manual) was spot on. I 
>> have 4,50V DC at TP1 and >1Meg-ohm across the battery terminals.
>> First power-on test went flawlessly - The FWD leds blinked, then the SWR 
>> leds, then the 1,4 / 14 / 140W scale leds.
>> Then things went acting funny. Powering the W1 from my MFJ 4125 power 
>> supply and running my K3 into the W1 and terminating into a known good 
>> dummy load I get perfectly accurate power and SWR readings when running 
>> no more than 1,4 watts. However, the W1 does not autoscale when my K3's 
>> output power goes above 1,4 watts. Whichever power I run, the W1 keeps 
>> showing the 1,4W green led and I get full scale FWD power readings.
>> I have also tested the W1 running on a 9V battery and I get the very same 
>> results.
>> The manual says that U4, running FW 1.05, should take care of 
>> autoscaling. but apparently there's something wrong here. The funny thing 
>> is that the SWR reading seems to be fine. Using 1W, 10W and 100W show 
>> consistent SWR readings.
>> Any thoughts on where I should look first? As stated before, the lowest 
>> power level shows perfectly accurate power/SWR readings.
>>
>> Thanks for any help
>>
>> Glenn ON4WIX
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>>
>
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