[Elecraft] KPA500 SWR Calibration

[ab2tc]

Hi all,

I am not familiar with the term "Breune" as applied to SWR bridges or
directional couplers, so I Googled it. As I suspected, it applies to the
single transformer design where the RF voltage is sampled by a capacitive
divider. While these can be made to work adequately well when properly
adjusted, the need for adjustment is a definite disadvantage. As long as the
two transformers in the two transformer design are well matched (ideally
identical) there is no need for any (balance or null) adjustment in this
design. I am happy to see that all of the Elecraft equipment I have seen use
the the two transformer design.

AB2TC - Knut


AJ8MH-Radio.Joe.Hutchens wrote
> I know I've seen an explanation somewhere, but it's common to have 
> different readings between the tuner, amp and rig when connected to an 
> antenna. Readings seem to even out when connected to a dummy load...at 
> least in my case. 20 meters is my worst, and the amp will kick out at
> times.
> 
> On 11/17/2019 2:19 PM, Bob McGraw K4TAX wrote:
>> Jack, et.al.
>>
>> Thanks,  Yes I see from the circuit it is not a Breune.   I have 
>> calibrated the indications for power and all is well in that regard.  
>> I just see a higher SWR that actually exists.  That under certain 
>> conditions causes the amp to fault.   I'll figure a work-a-round and 
>> be able to deal with it.
>>
>> 73
>>
>> Bob, K4TAX
>>
>>
>> On 11/17/2019 10:12 AM, Jack Brindle wrote:
>>> Bob;
>>>
>>> The KPA500 does not use a Breune style bridge, but rather a true 
>>> directional coupler. It does not need to be nulled; there is no 
>>> adjustment.
>>>
>>> There is an adjustment for the power; see the PWR ADJ setting in the 
>>> manual.
>>>
>>> 73!
>>> Jack, W6FB
>>>
> <snip>





--
Sent from: http://elecraft.365791.n2.nabble.com/