W1 Power Meter Checkout

[Brian Heinitz]

I completed assembly of the W1 and proceeded with the Checkout and Calibration.

1. Power-up was normal, with the Forward Power LEDs, SWR LEDs, and Range LEDs properly flashing momentarily in sequence, then the 1.4 Range LED remains illuminated.

2. The calibration was normal. With power on the system, I adjusted the CAL potentiometer for 4.5 VDC between the ground test point and TP1.

The only aspect of the checkout and calibration which was not normal was the resistance test across the battery holder terminal. With the power switch ON and no battery or DC power connected to the unit, the resistance should be > 1 megohm. With my DMM on 2M ohms selection, I receive a reading of 0.651, which is < 1 megohm.

I confirmed the orientation, location and values of all components, confirmed the quality of solder joints, and verified that there are no bridges. Unless I missed something, the assembly is correct.

Any thoughts on the resistance reading? Can I proceed with using the W1 or will this affect the accuracy of its operation?

Thanks!

Brian Heinitz
KI7LKB
[hidden email]
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

[Don Wilhelm]

Brian,

Were your fingers clear of the metal parts of the probes when you made
that resistance measurement?  If not, you may have been measuring the
resistance of your body.  That is common when making very high
resistance measurement.

73,
Don W3FPR

On 4/29/2017 5:11 PM, Brian Heinitz wrote:
> The only aspect of the checkout and calibration which was not normal was the resistance test across the battery holder terminal. With the power switch ON and no battery or DC power connected to the unit, the resistance should be > 1 megohm. With my DMM on 2M ohms selection, I receive a reading of 0.651, which is < 1 megohm.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

[Brian Heinitz]

Don,

Good tip. I just checked again, making sure I wasn't in contact with anything, and got the same result. I confirmed the accuracy of my DMM against several resisters from my spare parts inventory, and received accurate readings in the lower resistance ranges, but did not have anything in higher resistance, or enough smaller resisters to string together in series to verify the 2M range setting of the meter. It is a no-name meter I bought from a hardware store a few years ago, and I have a new one on my wish list. But at this point I have no evidence that this meter is inaccurate.

Although I have not had the opportunity to connect the unit to an antenna system, the rest of the functionality tests out fine so far.

Thanks!

Brian Heinitz
KI7LKB
[hidden email]

> On Apr 29, 2017, at 3:03 PM, Don Wilhelm <[hidden email]> wrote:
>
> Brian,
>
> Were your fingers clear of the metal parts of the probes when you made that resistance measurement?  If not, you may have been measuring the resistance of your body.  That is common when making very high resistance measurement.
>
> 73,
> Don W3FPR
>
>> On 4/29/2017 5:11 PM, Brian Heinitz wrote:
>> The only aspect of the checkout and calibration which was not normal was the resistance test across the battery holder terminal. With the power switch ON and no battery or DC power connected to the unit, the resistance should be > 1 megohm. With my DMM on 2M ohms selection, I receive a reading of 0.651, which is < 1 megohm.

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]