[Lowfer] [EXTERNAL]Re: A couple of crude Antenna Matching techniques - will either one work

[Howell, Laurence J]

Brian , in my case I was just being dumb and gained a learning experience - it was probably the power/freq/volts and age - something approaching 1.5kW offtune is very unforgiving

this was about 10 years ago :-)

Ive also got a .45/2MHz slug for my old battered 43 - and somewhere on you tube interweb theres a hellozerohellozero video comparing the 2-30 slug

Laurence
waiting for another plane....

> On Dec 1, 2017, at 8:50 AM, Brian, WA1ZMS <wa1zms at att.net> wrote:
> 
> I will retract the advice on the SWR bridge.  Guess I have been just fortunate or lucky when I tried mine.
> 
> But I also have a Bird slug for 450khz that has been my goldstandard for 630m SWR.
> 
> 
> -Brian, WA1ZMS
> iPhone
> 
>> On Dec 1, 2017, at 11:20 AM, Laurence KL7 L <hellozerohellozero at hotmail.com> wrote:
>> 
>> i also blew my weltz meter up 2-30MHz 1Kw trying it out on 137kHz - same issue, especially if off tune  - prob wrong ferrite material, lots of Volts, lots of smoke - there are a number of mf /lf swr bridge designs out there but the scope or metered version of the scopematch is probably cheapest/optimum though ive built that new VNA from Germany and though a little clunky on button pushes does the job without potentially letting smoke escape on wrong loads
>> 
>> Laurence
>> Seatac WA
>> 
>> 
>> 
>> On Dec 1, 2017, at 8:11 AM, John Langridge <kb5njd at gmail.com> wrote:
>> 
>>>> 1) Andy may be suprised how well his HF SWR bridge will work on 630m. The Pout readings may be off, but the null for lowest SWR will be there even if incorrect in magnitude.
>>> 
>>> This depends on how the sampling is accomplished.  I had an MFJ HF
>>> cross needle meter a few years ago that used ferrite sampling  which,
>>> based on discoloration of the core after use at MF, suggests that it
>>> got hot and probably exceeded the Curie point as it doesn't work
>>> anywhere now.
>>> 
>>> If you have one of the units that have closely space sampling bars
>>> tied to diodes and either dual meters or a switch to change forward
>>> and directed power, you could be ok but verify what you have first.  I
>>> didn't really care about burning up the MFJ meter anyway.  oh, btw,
>>> before that meter burned up, it read 2:1 SWR on MF no matter what the
>>> load.  On HF it was verified to be working properly into a good load
>>> until it finally failed.
>>> 
>>> 73!
>>> 
>>> John
>>> 
>>>> On Fri, Dec 1, 2017 at 9:54 AM, Brian, WA1ZMS <wa1zms at att.net> wrote:
>>>> My 2 cents on this.....
>>>> 
>>>> 1) Andy may be suprised how well his HF SWR bridge will work on 630m. The Pout readings may be off, but the null for lowest SWR will be there even if incorrect in magnitude.
>>>> 
>>>> 2) Tuning under TX power could be an issue for some TXs based on the class of operation the PA uses: Class A, B, C, D, E. Switch modes amps can act strange under active load pull. Any amp can too though.
>>>> 
>>>> 3) An ideal meathod for live tuning under TX power (for me) has been to place a 6 to 10dB power attenuator in the PA output path. The PA will run with a "reasonsble" load while you go outside and tune away for max antenna current. The RF po
> 
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