Moon-net August 2016

moon-net@mailman.pe1itr.com

164 participants
190 discussions

by Bryn Howell-Pryce

I’m just getting set up with version 1.7 of WSJT-X and see that a sound card sampling rate is specified whilst this is not the case with WSJT. If I change the settings to work with WSJT-X do these same settings work with WSJT? I would prefer not to have to change sound card settings for each program. 73 Bryn GW4ZHI

6 years, 9 months

Re: [Moon-Net] 6m EME Almost QRV

by Edward R Cole

Gedas, Interesting info on the transmitting caps. I'm using them in my 2m W6PO-8877 with no apparent issues. The filter I am building is from the QST article in Nov. 2002, pp34-38. This is a LP filter using flat brass plates insulated with teflon sheeting as the capacitors. I will check it on my HP141T using a low level signal. I has a tunable cap across the middle inductor for adjusting 2nd harmonic rejection and SWR at 50-MHz. I will make some photos of the finished filter to place on http://www.kl7uw.com/6m.htm 73, Ed At 04:50 PM 8/27/2016, Gedas wrote: >GM Ed, I am glad the information may be of some >use and interest for you. You will have to >forgive me for sending this to you via the >group, my ISP, for some reason will not deliver >an e-mail to you directly. I have tried to send >you hello's and other RF related mail for several years with zero success. > >Anyway, What I did to combat the fan noise issue >was to purchase (4) 48 VDC box fans then run >them at 24-28 VDC. There is still more than >enough air flow to keep the PA cool (even >running WSJT modes) and the noise goes down by >quite a bit. If I recall, the noise is a >non-linear function of RPM and you can gain a >lot or "quiet" by running them at a lower >voltage. The fans do not seem to mind running at >the lower voltage as they are cool as well. Just >a thought for you to consider. If you have any >questions etc feel free to ask, I will be happy >to do what I can. Oh, that image of the LPF >assembly.....that was an early prototype based >on the W6PQL design during the development stage >here at this end....the final filter looked >very similar but has some different part values. >The picture also does not show the other 1/2 of >the brass shielded enclosure and dividing wall. > >I learned something very, very interesting while >designing and building this filter. Since I >needed a significant amount of rejection in the >stop-band region I found that I had to use a >dividing wall within the LPF shielded enclosure >to reduce some inner-stage capacitive coupling. >That helped get me an additional 5-6 dB I.L. and >finally got me my -60 dBc specs met. > >But the most significant finding I had, at least >in my case, was that the values of the >capacitors I initially used were not very stable >as you used then at higher frequencies. Even >some expensive, good quality (new) and >high-current RF tramsmitting CD caps changed >their values as I went up in frequency. This was >NOT a thermal issue either. These caps were mica >wrapped around by silver sheet metal as plates >and are commonly used for RF transmitters etc. >In the end, my values were hand picked to >optimize the final Bode plot (which also you >have not seen). Below is an example of just 3 of >the typical caps that I measured. You can see >that in my case, for the caps I had on hand, the >simple Silver Mica caps proved to be the most >accurate and stable in terms of retaining their >value as they were used in the VHF region. Most >caps are rated (spec'ed at low frequencies). >Here is a quick plot showing the drop in >capacitance as the frequency was increased: > ><http://w8bya.com/var/albums/Misc/HAM-1/Different-Caps-1.jpg?m=1394322692>http://w8bya.com/var/albums/Misc/HAM-1/Different-Caps-1.jpg?m=1394322692 > > >Click on the image to expand it. I will see if I >can take some images of the final filter and >it's brass shielded enclosure with "dividing wall" if you like. > >73, Gedas > >----- Original Message ----- > >From: "Edward R Cole" <kl7uw(a)acsalaska.net> >To: "Gedas" <w8bya(a)mchsi.com> >Sent: Saturday, August 27, 2016 3:54:02 AM >Subject: Re: [Moon-Net] 6m-eme almost QRV > >Gedas, > >Thanks for the info. I haven't checked bias on >individual transistors, yet. Just quick tests to see what it would do. >One good indication is no noticeable heat in the >exhaust air so must not be driving them too >hard. Hell of a noise from those five fans. >Pretty much convincing me to remotely mount the >PS and amp on the tower at ground level running >240vac and control wires. If I did that I would >only need a run of RG-213 for drive power and my >transmission loss would be cut in half. > >I'm measuring RF power with Bird 1000A element >so accuracy is unknown. I have a 2500B element >and 500H element which I can make comparison >readings. I use the 2500B on 2m measuring my >8877. I'm pretty sure is reads low about 1300 >when running 1400w. I've compared it at 500w with a 500C element. > >I'm being more careful with dc current readings >since I can measure dc input power easily. > >Thanks, again. > >73, Ed > >At 04:30 PM 8/26/2016, you wrote: > > >Hi Ed and congrats on getting your Harris up and >running. It looks like you are in the final >stretch of the project and it will be >fascinating to see how your setup performs. I >wanted to share with you some data I collected >on my Harris 6m SSPA from a couple years ago >when I was first bringing it on line hoping you >may find some of the information interesting and >maybe even useful. Thanks to a wonderful EME >friend who let me borrow his high-power >Directional Coupler good from 6m on up to 500 >MHz (a Werlatone Model C3908), I was able to get >a pretty accurate picture of just how bad my >particular SSPA was in terms of spectral purity >(or actually lack of hi-hi). I found that my >solution required me to design and build my own >LPF assembly since 2xF0 and 3xF0 were so high. I >am not sure if it was just my particular unit >that was so dirty or if they are all like this. >I made sure before any measurements that all of >the MOSFET's were properly biased (400 mA rings >a bell if memory serves me right). > >I also seem to remember 2xF0 was a whopping -23 >dBc while 3xF0 was -47 dBc ! Nasty. I know a lot >of fellas assume that any available LPF assembly >rated for 1 kW will be adequate but after seeing >how bad my unit was I knew it was going to take >a bit more effort. Some people even think that >only the second harmonic needs to be filtered >which may be quite incorrect for their unit. > >I thought I would share with you a couple images >of what the raw spectra of my particular Harris >looked like going right into a 50 ohm load, then >what the spectra looked like after the home brew >LPF assembly. The final image show what the Bode >plot of the LPF looks like along with the >physical implementation. Best of luck. > >Gedas, W8BYA > >Gallery at <http://w8bya.com/>http://w8bya.com >Light travels faster than sound.... >This is why some people appear bright until you hear them speak. > >ï»¿ > >_______________________________________________ >Moon-Net posting and subscription instructions >are at http://www.nlsa.com/nets/moon-net-help.html 73, Ed - KL7UW http://www.kl7uw.com "Kits made by KL7UW" Dubus Mag business: dubususa(a)gmail.com

6 years, 9 months

Sensitivity Improvement - Why not Simply a Longer Sequence in JT65?

by Jimmy Blanchette

All, We know that going from JT65B2 (30-sec sequence) to JT65B (1-min sequence) provides a 3dB sensitivity improvement: http://mailman.pe1itr.com/pipermail/moon-net/2012-September/012540.html I am puzzled as to why versions of JT65 have not been developed with longer sequences (e.g. 2-3-4 min, etc.), which would be a very simple way to improve the sensitivity when more of it is needed (e.g. QSO with low ERP station). In addition to the mathematical fact that a longer sequence improves the signal-to-noise ratio "S/N", considering the fact that the libration effect can cause positive swings of many dB in the EME signals which may last for several seconds, wouldn't be possible to take advantage of this natural phenomenon and by averaging several of these longer sequences, extraordinary sensitivity gain could be obtained with relatively little effort? 73, Jimmy KK6FAH

6 years, 9 months

6m EME Almost QRV

by Gedas

GM Ed, I am glad the information may be of some use and interest for you. You will have to forgive me for sending this to you via the group, my ISP, for some reason will not deliver an e-mail to you directly. I have tried to send you hello's and other RF related mail for several years with zero success. Anyway, What I did to combat the fan noise issue was to purchase (4) 48 VDC box fans then run them at 24-28 VDC. There is still more than enough air flow to keep the PA cool (even running WSJT modes) and the noise goes down by quite a bit. If I recall, the noise is a non-linear function of RPM and you can gain a lot or "quiet" by running them at a lower voltage. The fans do not seem to mind running at the lower voltage as they are cool as well. Just a thought for you to consider. If you have any questions etc feel free to ask, I will be happy to do what I can. Oh, that image of the LPF assembly.....that was an early prototype based on the W6PQL design during the development stage here at this end....the final filter looked very similar but has some different part values. The picture also does not show the other 1/2 of the brass shielded enclosure and dividing wall. I learned something very, very interesting while designing and building this filter. Since I needed a significant amount of rejection in the stop-band region I found that I had to use a dividing wall within the LPF shielded enclosure to reduce some inner-stage capacitive coupling. That helped get me an additional 5-6 dB I.L. and finally got me my -60 dBc specs met. But the most significant finding I had, at least in my case, was that the values of the capacitors I initially used were not very stable as you used then at higher frequencies. Even some expensive, good quality (new) and high-current RF tramsmitting CD caps changed their values as I went up in frequency. This was NOT a thermal issue either. These caps were mica wrapped around by silver sheet metal as plates and are commonly used for RF transmitters etc. In the end, my values were hand picked to optimize the final Bode plot (which also you have not seen). Below is an example of just 3 of the typical caps that I measured. You can see that in my case, for the caps I had on hand, the simple Silver Mica caps proved to be the most accurate and stable in terms of retaining their value as they were used in the VHF region. Most caps are rated (spec'ed at low frequencies). Here is a quick plot showing the drop in capacitance as the frequency was increased: http://w8bya.com/var/albums/Misc/HAM-1/Different-Caps-1.jpg?m=1394322692 Click on the image to expand it. I will see if I can take some images of the final filter and it's brass shielded enclosure with "dividing wall" if you like. 73, Gedas ----- Original Message ----- From: "Edward R Cole" < kl7uw(a)acsalaska.net > To: "Gedas" < w8bya(a)mchsi.com > Sent: Saturday, August 27 , 2016 3:54:02 AM Subject: Re: [Moon-Net] 6m-eme almost QRV Gedas, Thanks for the info. I haven't checked bias on individual transistors, yet. Just quick tests to see what it would do. One good indication is no noticeable heat in the exhaust air so must not be driving them too hard. Hell of a noise from those five fans. Pretty much convincing me to remotely mount the PS and amp on the tower at ground level running 240vac and control wires. If I did that I would only need a run of RG-213 for drive power and my transmission loss would be cut in half. I'm measuring RF power with Bird 1000A element so accuracy is unknown. I have a 2500B element and 500H element which I can make comparison readings. I use the 2500B on 2m measuring my 8877. I'm pretty sure is reads low about 1300 when running 1400w. I've compared it at 500w with a 500C element. I'm being more careful with dc current readings since I can measure dc input power easily. Thanks, again. 73, Ed At 04:30 PM 8/26/2016 , you wrote: Hi Ed and congrats on getting your Harris up and running. It looks like you are in the final stretch of the project and it will be fascinating to see how your setup performs. I wanted to share with you some data I collected on my Harris 6m SSPA from a couple years ago when I was first bringing it on line hoping you may find some of the information interesting and maybe even useful. Thanks to a wonderful EME friend who let me borrow his high-power Directional Coupler good from 6m on up to 500 MHz (a Werlatone Model C3908), I was able to get a pretty accurate picture of just how bad my particular SSPA was in terms of spectral purity (or actually lack of hi-hi). I found that my solution required me to design and build my own LPF assembly since 2xF0 and 3xF0 were so high. I am not sure if it was just my particular unit that was so dirty or if they are all like this. I made sure before any measurements that all of the MOSFET's were properly biased (400 mA rings a bell if memory serves me right). I also seem to remember 2xF0 was a whopping -23 dBc while 3xF0 was -47 dBc ! Nasty. I know a lot of fellas assume that any available LPF assembly rated for 1 kW will be adequate but after seeing how bad my unit was I knew it was going to take a bit more effort. Some people even think that only the second harmonic needs to be filtered which may be quite incorrect for their unit. I thought I would share with you a couple images of what the raw spectra of my particular Harris looked like going right into a 50 ohm load, then what the spectra looked like after the home brew LPF assembly. The final image show what the Bode plot of the LPF looks like along with the physical implementation. Best of luck. Gedas, W8BYA Gallery at http://w8bya.com Light travels faster than sound.... This is why some people appear bright until you hear them speak.

6 years, 9 months

Re: [Moon-Net] [Moon] 6cm today

by Zdenek SAMEK-OK1DFC

Hi EME gang, I was QRV with my portable setup just only during Saturday AW EME window. I have to say, that activity were great and also my small portable unit works good. I was able to work 8 CW QSOs and 6JT QSOs. Looks that during next pedition I will be able to work many of you very easy. I have worked: OK1 KIR, JA1WQF, JA4BLC, UN6PD, UA3TCF, SM6CKU, G3LTF, SQ6OPG, OZ1LPR, UA3PTW and G4NNS. Heard HB9Q but did not work due to low elevation and Moon behind house. Sorry nobody from NA on the band till my Moonset. Thank you to all for nice QSO and looking forward to work many other in next future. -- Zdenek - OK1DFC www.ok1dfc.com QRV EME 144 MHz - 10 GHz WAC 432 - 1296 - 2320 MHz WAZ #9 DXCC 432 - 1296 MHz ---------- Původní zpráva ---------- Od: SM6CKU via Moon <moon(a)moonbounce.info> Komu: moon(a)moonbounce.info, moon-net(a)mailman.pe1itr.com Datum: 27. 8. 2016 15:04:58 Předmět: [Moon] 6cm today "Hello guys, Returning from a nice conference in Venice it was good to get back to 6cm after a long break. Now using a KX3 as IF and it is a joy. Friday I worked HB9SV and G3LTF and today Saturday G3LTF again, OZ1LPR, II3EME, OK1DFC, SV3AAF, UN6PD, SM6PGP, HB9SV again, OK1KIR and IK2RTI. Will try to get up early tmw but it is usually very hard.... 73 de Ben SM6CKU _______________________________________________ Moon mailing list Moon(a)moonbounce.info http://lists.moonbounce.info/listinfo/moon"

6 years, 9 months

2 instances of WSJT-X v1.7?

by Conrad PA5Y

I would like to start a second instance of WSJT-X so that I can have one on my H pol and one on Vpol. I have made several QSOs today with QRA64 Mode A but I feel lost without both polarisations. Switching from one to the other is not the same. I made 2 fresh installs into separate folders and named one configuration H pol and the other Vpol but still I am unable to run 2 separate instances on different audio interfaces. Perhaps someone can help me? I have not found any weak enough stations yet to test the improvements, I would also like a DF display rather than a frequency display on the waterfall and we should perhaps standardise on a TX Frequency, default is 1500, I have been using 1200Hz. Very interesting. I also see QRA64 signals much more clearly on the WSJT and MAP65 waterfalls than the WSJT-X waterfalls. Still a lot to learn. Regards Conrad PA5Y --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

6 years, 9 months

CO8LY on 2m EME

by Conrad PA5Y

Eduardo CO8LY is looking to try on eme at his moonset. He does not have a clear takeoff for Europe but will soon add elevation so that problem will be solved soon. He has a good 15 ele yagi with an 8m boom, short coax run and 50W only at the moment. All details are on QRZ.com I suggest that the bigger USA stations try with him and arrange a few skeds. He is familiar with WSJT from 6m operations. Lets help him any way we can, I will send him an LNA, it is difficult for him to receive items via the mail. He is committed enough to make a long yagi so try. European and Russian stations should not send hundreds of emails - yet! He will get there be patient. 73 Conrad PA5Y --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

6 years, 9 months

Re: [Moon-Net] 6m-eme almost QRV

by Gedas

Hi Ed and congrats on getting your Harris up and running. It looks like you are in the final stretch of the project and it will be fascinating to see how your setup performs. I wanted to share with you some data I collected on my Harris 6m SSPA from a couple years ago when I was first bringing it on line hoping you may find some of the information interesting and maybe even useful. Thanks to a wonderful EME friend who let me borrow his high-power Directional Coupler good from 6m on up to 500 MHz (a Werlatone Model C3908), I was able to get a pretty accurate picture of just how bad my particular SSPA was in terms of spectral purity (or actually lack of hi-hi). I found that my solution required me to design and build my own LPF assembly since 2xF0 and 3xF0 were so high. I am not sure if it was just my particular unit that was so dirty or if they are all like this. I made sure before any measurements that all of the MOSFET's were properly biased (400 mA rings a bell if memory serves me right). I also seem to remember 2xF0 was a whopping -23 dBc while 3xF0 was -47 dBc ! Nasty. I know a lot of fellas assume that any available LPF assembly rated for 1 kW will be adequate but after seeing how bad my unit was I knew it was going to take a bit more effort. Some people even think that only the second harmonic needs to be filtered which may be quite incorrect for their unit. I thought I would share with you a couple images of what the raw spectra of my particular Harris looked like going right into a 50 ohm load, then what the spectra looked like after the home brew LPF assembly. The final image show what the Bode plot of the LPF looks like along with the physical implementation. Best of luck. http://w8bya.com/index.php/Misc/HAM-1/Harris-LPF-1 http://w8bya.com/index.php/Misc/HAM-1/Harris-LPF-2 http://w8bya.com/index.php/Misc/HAM-1/Initial-6m-LPF-1 Gedas, W8BYA Gallery at http://w8bya.com Light travels faster than sound.... This is why some people appear bright until you hear them speak. ----- Original Message ----- From: "Edward R Cole" <kl7uw(a)acsalaska.net> To: moon-net(a)mailman.pe1itr.com, pnwvhfs(a)googlegroups.com Sent: Friday, August 26, 2016 7:04:41 PM Subject: [Moon-Net] 6m-eme almost QRV I ran tests on my Harris kW ch.2-TV amp today and can get 900w output with 10w drive. Amp draws 49 amp at 48.6v to deliver 900w (2381w dc input power; 1481w dissipated). I have to finish building my harmonic filter before declaring fully QRV. more info: http://www.kl7uw.com/6m.htm 73, Ed - KL7UW http://www.kl7uw.com "Kits made by KL7UW" Dubus Mag business: dubususa(a)gmail.com _______________________________________________ Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html

6 years, 9 months

Re: [Moon-Net] EME 2016

by Leif Asbrink

Hello All, The EME 2016 event was the best EME conference ever to me personally. Interesting results of real measurements were presented and results were not really as expected. Experiment wins above theory - particularly when theory is a sloppy guess.... Dominique, HB9BBD, wrote (on the MOON reflector) > GuysWhat I saw during this event was an IT conference, > interrupted by clowneries of a bunch of antenna builders. He also wrote things I do not want to copy.... I am well aware of Dominiques position, but it is not fair to say the EME2016 event was digital and antenna building only. I do not think Dominique would say "I already knew this" or "it is not relevant to CW operators" what I write below. I will try to explain the implications of two of the papers. G3WDG - Experiences with Circular polarization on 10 GHz and G4DDK - An investigation into EME LNA safe operating levels. It is well known (?) that on 10 GHz with linear polarization the loss when using the wrong polarization is about 11 dB http://www.sm5bsz.com/linuxdsp/usage/pol10ghz.htm Without really thinking I have assumed that the loss when using the wrong circular would be the same. Charlies lecture shows us something completely different!!! On page 101 of the proceedings we see that the signal from the Rx port is 8 dB stronger than the signal from the Tx port. That is the values obtained from the maxima in figure 6, page 101 in the proceedings. The spectral broadening in the Tx port is much wider than the broadening in the Rx port however. The 3 dB points are separated by 110 Hz while the 3 dB points in the Rx port are separated by 40 Hz only. That would mean that the power ratio would be 3.7 dB if the curve shapes were the same. That is not the case, the ratio is a little higher, maybe 4 to 5 dB. It is clear however that a lot of energy is lost in the orthogonal polarization. Charlie suggests "nearly 25% of the returned power from the moon is lost into the opposite [circular] polarization." Assuming a ratio of 4 dB (2.5 times) 71% of the power would appear in the Rx port and 29% would appear in the Tx port. By putting a second receive system on the Tx port one would get a second, independent signal. Sending both of them to the head-phones should improve sensitivity significantly. In case the signal is linearly polarized, using both circiular ports, one to each ear should improve sensitivity, by how much is unknown to me, but combining the two signals in the appropriate phase would provide linear polarisation aligned with the polarization of the incoming wave. >From figure 8 we learn that circular to circular is about 1 dB worse than linear to linear. That is a factor of 0.79 not too far from the guess based on figure 6. These are the conclusions I make based on Charlies paper: LP to LP has negligible loss. CP to CP has 1 dB loss CP to LP has 2 dB loss relartive CP to CP CP to opposite CP has 4 dB loss It was unexpected to me - but once I know it as a fact I think I can understand it. Halfway from the center the moon surface slopes by 45 degrees. Vertical (on the moon) surfaces form corner reflectors that reflect circular back to the earth with the wrong polarization while linear polarization is changed much less. Combining both circular ports on receive would give a 3 dB advantage (minus losses) if the other station is using linear polarization. When the other station is circular, combining ports incoherently will give a smaller advantage. When combining two signals S/N and 0.4S/N (power ratios) my guess is that the improvement would be something like a factor of 1.2 or just a single dB. It was pointed out in the discussions that big stations might prefer linear polarization on 10 GHz in order to be able to work terrestrial stations that have power enough, but use linear polarization. This will soon become far more important in the near future with the new algorithm developed by Nico IV3NWV that mostly eliminates the S/N degradation due to the spectral broadening. This will make 10 GHz EME about 6 dB easier than it is now with the best digital mode. This is very new, it is not in the proceedings, but there is a hint in the video from his lecture. It seems to me that the clever method to avoid S/N loss due to spectral broadening can be applied to CW also. Maybe with a slightly smaller advantage, but even a 3 dB improvement would be welcome I would think. Basically one would run many receive channels with a matched bandwidth of about 18 Hz for CW. The EME signal would spread over maybe 10 such channels. One would compute the probability of key up or key down for all the channels in a certain time interval and compute the product of all the probabilities. The probability that goes from 0 to 1 would be used to send something into the loudspeaker. Dominique and other CW operators might benefit from listening to lectures done by people who understand information theory. Most of it is about coding - but there are also other things... The paper by G4DDK shows us that it does not matter much for the survival of LNAs whether DC supply is on or off. The limit is in the order of 15 dBm in both cases. Note that these measurements are in a 50 ohm system. There seems to be a small advantage to have DC supply off. The advice "it does not matter much, but power off seems just a little better" is ONLY applicable when a relay is used to switch in a 50 ohm dummy. In situations where a relay is used to switch between Rx and Tx on the same antenna it is different. The recommendation to have DC supply on comes from practical experience. If one connects a conventional LNA to a conventional shorting relay such as the CX-520D on 144 MHz directly to a conventional LNA on 432 MHz one might use the attenuation -53 dB from the data sheet to compute the maximum allowed power on the Tx side. Based on Sams paper we might go for a 10 dB safety margin and tolerate 5 dBm into the LNA. That means one would believe that +58 dBm would be the maximum safe Tx power. (=630W) This belief is wrong. The output impedance of the relay is 7nH with a resistive component of about 0.4 ohms. When the CX-520 is used on 432 MHz with 630 W Tx power it would produce 5 dBm into a 50 ohm load, it means that there would be 0.4 V rms across a 50 ohm load. If instead we connect a matched load, 0.4 ohms (plus the appropriate reactive part), something we might have in an unpowered LNA, we would have 0.2 V rms across 0.4 ohms which is +20 dBm (100 mW) and definitely more than a LNA would survive. In case we keep the LNA powered, thi input impedance will stay closer to 50 ohms and power transfer will be much smaller and the LNA would survive. I think this is the explanation why practical experience suggests one should leave the DC voltage on. If you want to use a relay with poor isolation, look here: http://www.sm5bsz.com/pindiode.htm When both the relay and the LNA are very far from 50 ohms we can select the cable to produce the largest possible mismatch between the LNA and the relay. That would increase attenuation dramatically and it works best when the LNA is unpowered. It is interesting to note that the impedance of the LNA changes when the gate current starts to flow. When the supply voltage is zero, gate current starts to flow at modest power levels. The gate current will change the impedance at the gate from very high to very low. One has to select the cable length for minimum gate current at power levels high enough to produce gate current. (If there is never any gate current - isolation is high enough and DC on or off would not matter.) Conclusion: The best advice is to make sure the LNA always has 50 ohms on its input. Then one can trust Sams study and not worry about whether the LNA is powered or not. Under certain circumstances it is however possible to get an advantage. The extra relay is likely to introduce more losses than a cable that maximizes the mismatch between the relay and the LNA. Nominal attenuation in a 50 ohm system does not have to be particularly high to make an unpowered LNA survive.

6 years, 9 months

6m-eme almost QRV

by Edward R Cole

I ran tests on my Harris kW ch.2-TV amp today and can get 900w output with 10w drive. Amp draws 49 amp at 48.6v to deliver 900w (2381w dc input power; 1481w dissipated). I have to finish building my harmonic filter before declaring fully QRV. more info: http://www.kl7uw.com/6m.htm 73, Ed - KL7UW http://www.kl7uw.com "Kits made by KL7UW" Dubus Mag business: dubususa(a)gmail.com

6 years, 9 months

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Moon-net August 2016