SRI Wrong link http://www.antennas-amplifiers.com/Band-Pass-Filter/50MHz-Bandpass-Filter-B… 73 http://www.antennas-amplifiers.com http://www.dual.rs On 03.03.2016 00:32, Dual wrote: _______________________________________________ Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html

Hello Chris, You raise a point that I was pondering with here, as I intend to put up a stack of 50/144/432 Yagis (one per band). The coupling will have to be measured, because I will have 2 radio front ends and 2 preamps to protect from the RF on the other bands. (This is not specifically for EME, instead terrestrial mainly). In the past on 144MHz EME I always used separate TX and RX feed lines, which simplified things to an extent, though I did once blow a front end because I had insufficient isolation on the main changeover relay and the preamp was bypassed, but the front end was not disconnected on transmit. Once I fitted another relay on the front end that cured that. I have a good low pass filter on 144 on the output of the PA, but the problem still would be that the coupled power at 144 would or could overload the 432 preamp or front end. I suppose some form of interlock could be devised similar to your switching other rigs to TX to prevent this problem. I do have cavity bandpass filters for 144 and 432 that I could use in the shack ahead of the receivers but I was hoping to avoid them as they do introduce loss, admittedly after the preamp and they have to be suitable for the low level transmit power, about 3 watts which is no problem. I won't even have the preamps fitted to start with as I have a run of low loss feedline which makes 144 weak signal work possible without a masthead preamp as the transverter has a low enough NF. I am curious to know what others do, there must be many others with Christmas tree stacks on VHF/UHF with multiple rigs. I won't be running QRO on 432 or 50 to start with, though I do on 144, so it is mainly the 432 front end that I am worried about protecting. I read that a lot of times peamp devices go slightly bad, but don't blow completely when subjected to high levels of RF (G4DDK has experience of this recently with his VLNA and has blogged about it). So I guess it comes down to trying to reduce the coupling between antennas, then if the level is still unsafe, either bandpass filtering the front ends without degrading the noise figure by adding more loss, or having suitable relays to disconnect the antennas from the front ends while transmitting on the other bands. Let's hear from other VHF UHF contesters/rovers - what do you do? You may want to reply privately as this may be OT for EME, but maybe not. 73 David GM4JJJ On Fri, 11 Mar 2016 at 01:02, Christopher E. Brown &lt;cbrown(a)woods.net <mailto:cbrown@woods.net>> wrote: What I would really love to find is wider TX capable bandpass filters that are low loss for whole band on 6M, 2M, 70cm My "weak signal" setup is HOA limited, and I run 3 seperate radios, meaning strong coupling between antennas on those bands is a major issue. I can of course place a RX only filter in front of pre-amp, but I really need to place upstream of pre-amp relays to protect radio as well (I currently have to power off pre-amps and switch to gnd both other rigs to TX as I do not like hiting pre-amp or radio with +20dbm or more. Something like < .2db 50-54 -60db or better at 2M and 440 and capable of handling say 1KW and similar for 144-148 and 420-450 would make my day, because so far my attempts to build have not turned out so well. On 3/10/2016 12:30 PM, Dual wrote: and LNA. http://www.antennas-amplifiers.com/Band-Pass-Filter/6m-Bandpass-Filter-BPF > 73 Goran Yu1CF <http://www.antennas-amplifiers.com>http://www.antennas-amplifiers.com HF DXpeditions with lots weak signals.... very good. My preamps are I brought a spectrum to see near in out if band > signal +50 db hotter than my EME band noise. > After installing the 144-146 filter - out of band junk was substantial reduced (per rx noise levels dropped 20 > db but more traces are visible (decode) at much lower levels. > This is my glowing review. Filter A++ > 73 - Paul - W2HRO >> On 3/2/2016 23:41, Dual wrote: >>> Maybe someone will find interesting. >>>> >>>> Low loss (0.11 dB) Bandpass filter for 50 - 51 MHz >>>> http://www.antennas-amplifiers.com/Band-Pass-Filter/50MHz-Bandpass-Filter-B… >>>> >>>> 73 Goran YU1CF >>>> http://www.antennas-amplifiers.com >> >> > _______________________________________________ > Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html _______________________________________________ Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html _______________________________________________ Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html

SRI Wrong link http://www.antennas-amplifiers.com/Band-Pass-Filter/50MHz-Bandpass-Filter-B… 73 http://www.antennas-amplifiers.com http://www.dual.rs On 03.03.2016 00:32, Dual wrote: _______________________________________________ Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html