[TowerTalk] Fwd: Tower and antenna decisions

[Roger (K8RI) on TT]

On 10/30/2013 11:06 AM, Gene Fuller wrote:
> A simple "line flattener", and some hardline, pretty near moves a 
> station located "tuner" to the antenna, giving probably as much or 
> more radiated power and a lot more convenience. Exceptions of course 
> for  VHF and higher.
> Gene / W2LU

Line Flattener? I'd not heard that term before.

73

Roger (K8RI)
>
> ----- Original Message ----- From: "Roger (K8RI) on TT" 
> <K8RI-on-TowerTalk at tm.net>
> To: <towertalk at contesting.com>
> Sent: Sunday, October 27, 2013 1:25 PM
> Subject: Re: [TowerTalk] Fwd: Tower and antenna decisions
>
>
>> On 10/27/2013 10:10 AM, Jim Lux wrote:
>>> On 10/26/13 8:15 PM, Hans Hammarquist wrote:
>>>> All these "modern", solid state, PA have the same problem, they are 
>>>> "protected" and the "protection" rolls back the power as soon as 
>>>> they detect reflected power. Little depending on make and design 
>>>> they roll back more or less. That's why the manufacturer offer 
>>>> built in tuners. The "old days" with a pi-filter on the output 
>>>> could be tuned to most anything below SWR of 1:3 or even more, and 
>>>> they didn't have (needed maybe) the "protection". As long as you 
>>>> didn't kill the final tubes by overheating them, you were OK. Do we 
>>>> like to have the "old" tube final back? Maybe.
>>>>
>>>
>>> I would rather have "smart antennas" with the finals *at the 
>>> antenna* and the matching done there.
>>
>> This gets back to what I want to do...sorta.
>> Particularly on 160 you don't have a lot of room to make frequency 
>> excursions and that is to put the tuner "at the antenna", but that 
>> comes with a location that is hazardous to the tuner's health. 
>> Another is just how good are the remote autotuners?  Will they take 
>> the SWR right down to 1:1 which is important for SS amps, not because 
>> of power, but because of deteriorating signal quality.
>>
>> With a remote tuner, I want to match the antenna impedance, not just 
>> move the resonant point.  Yes, if I move the resonant point to cover 
>> the entire band it does make life easier and I could take care of the 
>> rest in the shack, but again I'd prefer to do this at the antenna so 
>> in most cases I only need a small L network even for 160 if it's 
>> close to resonance.
>>
>> With the half sloper other than the difficult maintenance problem 
>> this becomes rather easy although on 160 that makes for a lot of 
>> resonant points.
>>
>> putting the matching network at the antenna for a center fed, half 
>> wave, sloping dipole is not practical although a single band tuner at 
>> the tower using open wire line might.  Ice storms are common here 
>> spring and fall, although there are far fewer in the fall but the 
>> make open wire problematic and to me, reliability/durability is 
>> important because I have to impose on others to get things fixed.
>>
>>>
>>> Sure, it's more complex than the historic Transmitter in 
>>> Shack/Feedline/Fixed Antenna, but life moves on.
>>>
>>> For instance, I sketched out an interesting design for a form of 
>>> Yagi with all driven elements, using an array of magnetic loops, 
>>> rather than the traditional horizontal elements. The matching from 
>>> low Z semiconductors to the low Z of the magnetic loop is actually 
>>> kind of what you want.   And you're doing spatial combining, so with 
>>> 5 elements, each driven with a 200W module, you don't have the 
>>> losses in the power combiner you see in a "single output" SSPA.
>>>
>>>
>>> Combine this with things like polar modulation, and you can get some 
>>> very interesting designs. It's almost like having the entire rig at 
>>> the top of the tower, and all you need is power and an ethernet 
>>> link, which could be wireless.
>>>
>>> Sure, its nothing like ham radio in the past, but that's what ham 
>>> radio is all about: try new things.
>>
>> I like the idea and to me it's far less different than a remote 
>> regular station, controlled over the internet. You're just combining 
>> the rig with the antenna. There might be issues with lightening, 
>> maintenance, and cost though.  Could it be made to match the big mono 
>> band Yagi for performance?
>>
>> It's a radical design, but used much the same way as ham rigs have 
>> since day one.
>>
>> 73
>>
>> Roger (K8RI)
>>
>>
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