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

[John Langridge]

>Does anyone here use a vertical antenna with a top hat for
transmitting?

most of us on the air today do.

On Fri, Dec 1, 2017 at 10:12 AM, Zack Widup <w9sz.zack at gmail.com> wrote:
> Does anyone here use a vertical antenna with a top hat for
> transmitting? At least on 630 meters? The local road conditions
> station in this area provided by the county transmits on 540 kHz and
> uses such an antenna.
>
> 73, Zack W9SZ
>
>
> On Fri, Dec 1, 2017 at 10:06 AM, Douglas Williams
> <williamsdoug1966 at gmail.com> wrote:
>> I wonder how close attaching an NE-2 to the hot end of the coil and tuning
>> for maximum brightness would get you?
>>
>> On Fri, Dec 1, 2017 at 10:54 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 power and current at the antenna will be much lower, but
>>> also less chance of getting RF burns as you tune and poke around. An
>>> attenuator might be cheaper (homebrew) than an antenna analyzer.
>>>
>>> 4) I've done all the above for 2200m & 630m myself.
>>>
>>> -Brian, WA1ZMS
>>>
>>> > On Dec 1, 2017, at 10:14 AM, John Bruce McCreath <weazle at hurontel.on.ca>
>>> wrote:
>>> >
>>> >
>>> >
>>> > Hi Andy….can you clarify a few things for me.  Is the bottom end of your
>>> coil grounded, is the capacitor
>>> > in parallel with the coil, are you tapping the feed line inner conductor
>>> near the bottom end of the loading
>>> > coil, and is its shield connected to the bottom of the coil/cap?  If
>>> that’s the case, you should be able to
>>> > bring it all to resonance with the meters you have.  I wouldn’t put an
>>> RF ammeter at the top end of the
>>> > loading coil, as it could really throw things off because of the high
>>> voltage there.  The antenna current
>>> > should be the same, regardless of whether it’s measured at the “cold” or
>>> “hot” ends of the coil.  Do you
>>> > have a means of measuring the transmitter final current?
>>> >
>>> > By comparison, here is how I resonated EAR’s antenna.  The loading coil
>>> has a built-in variometer for
>>> > adjusting resonance.  I put a current-transformer type RF ammeter on the
>>> ground end of the coil and
>>> > watched for a peak while I rotated the inner coil of the variometer.  To
>>> match the final to the loading
>>> > coil/variometer, I used a three turn link coil wound over the very
>>> bottom turns and moved it around
>>> > while watching for a dip in the final current.
>>> >
>>> > 73, J.B., VE3EAR
>>> >
>>> > LowFER Beacon "EAR"
>>> > 188.830 kHz. QRSS30
>>> > EN93dr
>>> >
>>> >
>>> >
>>> >
>>> >
>>> > ______________________________________________________________
>>> > Lowfer mailing list
>>> > Home: http://mailman.qth.net/mailman/listinfo/lowfer
>>> > Help: http://mailman.qth.net/mmfaq.htm
>>> > Post: mailto:Lowfer at mailman.qth.net
>>> > Post must be less than 50KB total for message plus attachment!
>>> >
>>> > This list hosted by: http://www.qsl.net
>>> > Please help support this email list: http://www.qsl.net/donate.html
>>>
>>> ______________________________________________________________
>>> Lowfer mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/lowfer
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Lowfer at mailman.qth.net
>>> Post must be less than 50KB total for message plus attachment!
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>>
>> ______________________________________________________________
>> Lowfer mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/lowfer
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Lowfer at mailman.qth.net
>> Post must be less than 50KB total for message plus attachment!
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
> <div id="DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><br />
> <table style="border-top: 1px solid #D3D4DE;">
>         <tr>
>         <td style="width: 55px; padding-top: 13px;"><a
> href="https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon"
> target="_blank"><img
> src="https://ipmcdn.avast.com/images/icons/icon-envelope-tick-round-orange-animated-no-repeat-v1.gif"
> alt="" width="46" height="29" style="width: 46px; height: 29px;"
> /></a></td>
>                 <td style="width: 470px; padding-top: 12px; color: #41424e;
> font-size: 13px; font-family: Arial, Helvetica, sans-serif;
> line-height: 18px;">Virus-free. <a
> href="https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link"
> target="_blank" style="color: #4453ea;">www.avast.com</a>
>                 </td>
>         </tr>
> </table><a href="#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2" width="1"
> height="1"></a></div>
> ______________________________________________________________
> Lowfer mailing list
> Home: http://mailman.qth.net/mailman/listinfo/lowfer
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Lowfer at mailman.qth.net
> Post must be less than 50KB total for message plus attachment!
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html