Art I don't know where this coming from ,but the gain you need for a VWF modest size is 20db for vertical polarization and for horizontal HWF you need 40db on 160m, on 80m divide this by 2, you need only 20 dB and on 40m 10 dB a NORTON preamp is enough. All situations you need a band pass filter.
The WF change gain with high above ground but the RDF and elevation angle does not change, only the gain change, for 160m, changing the antenna height 120 ft. to 90 ft. the gain drops 2 dB, from 90 to 60 the gain drops 3 dB more, and from 60 to 30 ft. 5 dB more, do for 160m HWF at 120ft the gain drops 10 dB for a 30 ft. high HWF. KD9SV sells a preamplifier that I recommend, it is special designed for WF's, check DXE page. You can check some WF results on Doug page, NX4D. I heard over 295 countries since 2006 using WF's, Doug heard over 300 and worked 295 on 160 since 2003, both of us live in subdivisions and we use a 40 dB gain preamp with tuned input and band pass filters after it. http://nx4d10.wix.com/waller-flag Detuning the tower or TX vertical antenna is a " MUST " for VWF. Not a problem for HWV. Inverter V also needs to be detuned in both cases. I recommend don't waste your time if detuning is not on top of you to-do list. Remove common node noise with chokes should be the second on the list, Antenna and preamp is the last thing to get going. Regards JC N4IS -----Original Message----- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Arthur Delibert Sent: Sunday, September 06, 2015 1:40 PM To: topband@contesting.com Subject: Topband: Waller Flag Question The on-line materials about Waller Flags says that a modest size WF would need about 40 dB of gain to boost the signal to a usable level. One of the postings says that cascading two preamps of 20 dB each seems to add extra noise, and they talk about developmental work being done on a single preamp of 40 dB. Is there now such a 40 dB preamp? Is it made commercially? Alternatively, are there plans on-line somewhere? Has someone actually used it in a high-RF urban/suburban area, with multiple 50 kW AM BC stations? With what results? Many thanks. Art Delibert KB3FJO _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband