[Elecraft] DMM recommendations

[hawley, charles j jr]

Bird did make a 10 Watt slug a few years ago, but there must not have been many of them and the on line Bird seller had one at a very high price. Like two times the regular price. It sold immediately as I remember.
I used a couple Birds attached with an N union and had a 25 in the rev and a 1K in the fwd with peak detector. It was a good setup.
I generally don't even need a wattmeter, but set one up mostly as a project more than any other reason..

Chuck Hawley
 c-hawley at illinois.edu

 Amateur Radio, KE9UW
 aka Jack, BMW Motorcycles
________________________________________
From: elecraft-bounces at mailman.qth.net [elecraft-bounces at mailman.qth.net] on behalf of Joe Subich, W4TV [lists at subich.com]
Sent: Monday, March 19, 2018 8:29 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] DMM recommendations

> When taking reflected power readings the slug should be 1/10 of the
> forward slug value when testing a reasonably good antenna. So, a 100
> watt forward slug would require a 10 watt reverse slug for reasonable
> accuracy.

Unfortunately, the smallest HF slug Bird make is 25 Watts.  That means
any SWR less than 1.4:1 (2.8% reflected power) is suspect with a 100 W
transmitter.  It is a shame that Bird do not offer a 10 (or 5 W HF
element) and the one reason I moved to the LP-100(A) several years ago.
However, I would never think to take the LP-100(A) or microHAM SMΩRF
out into the field.

73,

    ... Joe, W4TV


On 3/19/2018 8:10 PM, JOE wrote:
> I spoke to someone at Bird (when they were really Bird) years ago and I
> was told that the Bird wattmeter is accurate to ±5% of top scale.  This
> means that a 100 watt slug can be off ±5 watts _anywhere_ on the meter.
> So, a transmitter emitting 50 watts out, using the Bird and a 100 watt
> slug, can read between 45 and 55 watts.  That's why he said it was
> important to keep the reading in the top 1/3 (highest) end of the
> meter.  This is where the error is less.  When taking reflected power
> readings the slug should be 1/10 of the forward slug value when testing
> a reasonably good antenna.  So, a 100 watt forward slug would require a
> 10 watt reverse slug for reasonable accuracy.
>
> I retired my Bird 43 and the vast assortment of slugs for a Telewave
> Model 44A wattmeter and never looked back.  The drawback to the 44A is
> it is limited to 20-1000MHz.  The Bird would be good for HF use.
>
> 73, Joe, K1ike
>
> Date: Mon, 19 Mar 2018 18:40:41 +0000
>> Always bear in mind that their odd meters (30 uA) are very non-linear and
>> measurements made using element ranges that fall in the bottom 1/3 or
>> so of
>> the scale are the most accurate.  Overall, they claim to be accurate
>> to +/-
>> 20 percent of full scale.  HORRIBLE in
>> today's world!
>>
>> FWIW ...
>>
>> 73!
>>
>> K0PP
>
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