Ken, Thanks for the explanation - though I would have thought that the result of using the diode in the example you mention (D9) would be that there was still...
2009
K.Greenough
g0wbm
Apr 2, 2011 4:28 pm
Hello Lee, Steve could give a more definate answer but I think the signal levels are too small to bias the diodes on [approx' 700 mV needed]. 73 Ken g8beq ...
2010
Steve Drury
hamlab3
Apr 2, 2011 4:45 pm
Yes, from the DBM there is only around -16dBm or about 50mV RMS into a 50R load. Steve G6ALU...
2011
g3sew
Apr 2, 2011 5:48 pm
Thanks Steve and Ken All understood now! By the way, I have just managed to hear Sunrise Radio on Mick's MKARS on 3.542MHz on my antenna (but nothing heard on...
2012
Pascal
pascalv29
Apr 3, 2011 8:55 am
Hi Steve, The frequency moves suddenly when transmiting for less than one minute - This morning, I switch on the Mkars half an hour before the net, it looks...
2013
woodiescbj
Apr 3, 2011 9:34 am
Good morning, I could hear the net this morning but only r2 s2 on the banks of the river Rhein in Bonn, maybe I will have better luck next week, 72/3 de DD5CF...
2014
g3sew
Apr 3, 2011 10:02 am
Pascal, When you transmit, does the power supply voltage remain stable? If not, that could be the problem. Good to hear everyone on this morning by the way....
2015
Pascal
pascalv29
Apr 3, 2011 2:03 pm
Hi Lee Yes voltage is stable, between 13.5 and 13.6 V - Frequency seems to stabilize after on hour, which is a long time... The net hour is late in the...
2016
g4dfv
Apr 3, 2011 2:26 pm
Perhaps a more suitable time for the MKARS net would be in the evening when propagation may be better? Duncan G4DFV [Non-text portions of this message have...
2017
g3sew
Apr 4, 2011 7:48 am
Pascal, Is this a new fault, or has it always been like this? And does it properly stabilise on receive? With mine, as soon as I have turned on the power it...
2018
Pascal
pascalv29
Apr 4, 2011 7:10 pm
Lee, This fault is from the beginning - I suppose the drift of the VFO is too high to allow the varicap to correct it a long time, so the system switch off the...
2019
sa3azk
Apr 4, 2011 9:03 pm
Hi Pascal Had about the same problem with my mkars 80, It suddenly snapped out of lock. I cured the behaviour on my kit by replacing R40 with a 8k2 resistor,...
2020
Steve Drury
hamlab3
Apr 4, 2011 9:10 pm
Pascal, Does the display normally show a "+" without any bars or does it always show bars as well, for instance " --+ " or " +-- " ? The easiest thing...
2021
Jonathan point
vk2jdp
Apr 4, 2011 11:20 pm
Pascal, ... << I assume that you have everything mounted solidly in the case. >> My MK' had a bad drift to it when I built a small linear into it, but that was...
2022
g3sew
Apr 5, 2011 8:27 am
Pascal, Happy to try 17.00GMT Wednesday evening on 3.69 - OK? But will your VFO be stable enough to have a QSO? I would have thought that it was more likely...
2023
K.Greenough
g0wbm
Apr 5, 2011 9:17 am
Hello Lee, I notice from several of your mails on your interference problem that you have concentrated on the low pass filter, but of course a low pass filter...
2024
g4dfv
Apr 5, 2011 9:44 am
I don't know about 80m conditions at others QTH's, but in the morning at my location most signals on the band are incredibly quiet, many right down in the...
2025
g3sew
Apr 5, 2011 9:48 am
Ken, I was suspicious of the LPF because it seemed that if I introduced the antenna after the LPF, the problem was reduced. I was not thinking that the LPF...
2026
g3sew
Apr 5, 2011 9:53 am
Duncan, I think you are probably right about the time. 18.00 GMT would be better for long distance propagation (though it might be more noisy). What do you...
2027
g3sew
Apr 5, 2011 6:59 pm
Hi, I am still trying to track down why I get images and intermod on my MKARS. Tracing a signal through from the antenna socket, my MKARS has massive amounts...
2028
panzerbeeb
Apr 5, 2011 7:32 pm
Lee, when you say the waveform has some distortion, is it basically unsymetrical from positive to negative half cycles? If so it might be worth checking the...
2029
Steve Drury
hamlab3
Apr 5, 2011 7:59 pm
Yes I would go for the same although I've no idea how we ended up with duff diodes! If that doesn't cure it rewind the mixer transformers, if you want to be...
2030
Pascal
pascalv29
Apr 5, 2011 8:13 pm
Hi I am ok for 18 GMT, 19 local french hour tomorrow, Wednesday Hope to hear you tomorrow around 3690 Pascal...
2031
John Tyler
g4gcl
Apr 6, 2011 10:39 am
I see that this item did not sell and is now re advertised at, what I would consider, a more reasonable starting price. It can be found here ...
2032
g3sew
Apr 6, 2011 10:45 am
Steve, There appear to be no bridges on the PCB - and Yes - I would very much appreciate a new set of diodes and ferrites. Thank you very much. In answer to...
2033
panzerbeeb
Apr 6, 2011 12:31 pm
Lee, That is exactly the effect you get if there is a duff diode in the bridge, change all four diodes first- it's the easier than rewinding T4, the mixer...
2034
g3sew
Apr 6, 2011 3:35 pm
Unfortunately it looks as if the diodes are OK. I have taken out T4 and T6, and they all look fine, with no shorts, and each pair of leads registering around...
2035
Pascal
pascalv29
Apr 6, 2011 5:09 pm
Unfortunatly, at 18GMT today, nothing heard, propagation was not there I will try later, 19 GMT...
2037
g3sew
Apr 7, 2011 3:21 pm
Fixed it at last! It turned out to be a broken track in the mixer between L6 and one of the diodes. All the diodes remained connected, so they passed the...
2038
Steve Drury
hamlab3
Apr 7, 2011 6:24 pm
Lee, Congratulations on finding it, I'm glad its working OK now. I have to ask this.... was it our problem or yours? The PCBs should be bare board tested...
