Topband: Rohn 25 Vertical questions.

[GEORGE WALLNER]

At C6AGU I have in-band RX on all bands. The rigs are Flex 6000 SDR-s. On 
160 m I can hear virtually unimpaired to about 12 kHz off the TX frequency. 
RX antenna is 4 direction delta loop, about 1000' from the TX vertical. The 
RX path includes a high performance RX pre-amp. (The RX antenna "gain" is 
-32 dBi.)
SDR-s can work for in-band RX, but you must have a very "clean" RX (and TX) 
paths and plenty of antenna separation. Also, lots of shielding and 
grounding.

73,
George,
AA7JV/C6AGU


On Thu, 20 Aug 2020 15:17:29 -0700
  "Richard (Rick) Karlquist" <richard at karlquist.com> wrote:
>
>
> On 8/19/2020 10:28 PM, donovanf at erols.com wrote:
>> Hi Ron,
>>
>>
>> 700-1200 foot spacing should provide good in-band receiving capability.
>> SDR receivers won't work for in-band receive, you must use a traditional
>> transceiver such as the K3, K4HD, FTdx5000, IC-7800 etc.
>>
>>
>> Micro-arcing is caused by transmitted RF jumping a spark gap.
>> Any metal-to-metal joint that isn't securely bonded is a candidate
>> for micro-arcing.
>>
>>
>> 73
>> Frank
>> W3LPL
>>
> Three questions:
>
> 1.  Does "in-band receiving" mean the same thing as SO2R in a single
> band contest?  I operated a few 160 meter contests in that mode around
> 10 years ago.  I used a carefully nulled receiving loop 1000 ft from the
> TX vertical.
>
> 2.  Please explain the comment about SDR receivers not working.  I
> now have a Flex 6700 that claims to be able to do full duplex.  And
> that radio would not work?
>
> 3.  If connections between R25 sections cannot be trusted, then
> how would any crank up tower possibly work as a vertical?  I have
> always wondered about this.
>
> BTW, cellular sites have significant problems with what they
> call "passive IMD", of which micro-arcing is a subset.
>
> 73
> Rick N6RK
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector