Message-ID: <43464DACBFAA49C08A73FB93FFF52105@gnat>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <1541636554.20151013163425@chriswilson.tv>
Date: Tue, 13 Oct 2015 18:14:43 +0100
MIME-Version: 1.0
Subject: LF: Re: Should I be aiming for a better match than this?
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Status: O

>>can i work out the antenna current from this?
Not really this is the current in the coax. If the current and voltage are 
not in phase then by definition you have reactance in the coax termination. 
You should try adjusting the variometer for current and voltage in phase 
(that is resonance) , then adjust the turns ratio on the transformer to 
match the resultant aerial resistive component to the 50ohm coax (if 
possible :-))  ) That should give you optimum performance.

The reactive load may be what is tripping the protection it will give bigger 
voltages(or currents) than the matched condition.

Whilst you have been getting a signal out, I suggest the next experiment is 
to try and reducethe ground loss before you spend a lot of time getting a 
perfect match to an imperfect aerial system (only to have to do it all again 
when you manage to get the ground loss down.)

Alan
G3NYK

----- Original Message ----- 
From: "Chris Wilson" <chris@chriswilson.tv>
To: <rsgb_lf_group@blacksheep.org>
Sent: Tuesday, October 13, 2015 4:34 PM
Subject: LF: Should I be aiming for a better match than this?


> 13 October 2015
>
>
> Got my (brave...) friend adjusting the variometer in real time whilst
> I talked to him by phone, and whilst transmitting at one setting below
> full power. I watched the `scope in the shack for best results. Is
> this an adequate match or should I get better than this? I think it's
> a resistive mismatch that's showing? It's a pain not having a colour
> scope but I am pretty sure it's amps leading volts being shown here.
> On full power the amp trips out, not sure if it's SWR mismatch or
> current overload. Will need to check that out. No arcing at the
> matching and loading coils though.
>
> http://www.chriswilson.tv/best-match.jpg
>
>
> I  built  the  Jim  Morittz  scopematch  using  the  capacitive divider
> circuit, can i work out the antenna current from this? Thanks.
>
> 2E0ILY
>
>
>
> -- 
>
>
> Best regards,
> Chris                            mailto:chris@chriswilson.tv
>
>