[Moon] [Moon-net] 1296 EME 10feb.

[w2drz]

Hi Viggo,

You have the tubes not completely biased off,
 add about + 50 volts to the cathode and ground in the stand by
condition.

This will apply a negative 50 volts to the grid and then be cutoff for
the tubes.

Measure what the cathode voltage is "now" in standby,
 I believe you will find it to be about + 25 to + 35 volts,
 this is the almost cutoff voltage.

That allows micro amps to flow, the tubes are then a noise diode
condition/mode.

I find on my 4 tube unit (+ 50 volts on cathode to ground) cuts the
tubes off and no diode noise out of tubes.

 I use a 1K to 3K ohm 2 watt resistor in series to the + 50 volt supply
to relay contact (N.C.) contact to the cathode relay common contact.

 Then when the relay common changes to the (N.O.) contact,
 for the inserting the 10K cathode resistor in series to cathode,
 use the (N.C.) contact to the 2K resistor to the +50 volt supply.

tom W2DRZ



Viggo Magnus LA9NEA wrote:
> 
> Hello!
> 
> Worked this fine 1296 cw EME stations to day.
> 
> SP6JLW  449/559, G3LTF 569/569, DF3RU 559/559, ON7UN 579/579, OK1DFC 559/579.
> 
> approx 1430z SM5LE called me but no qso,SM5LE write on E mail this afternoon, he had an solid tree-block so signals was weak.....
> 
> Plan to be qrv next wekend  if wx stay ok.
> 
> I found  my PA ( 6x 7289 water-cooled) give me some noise in RX period, with my sun noise meter I found 1.4 dB  noise on RX from the PA./ and  no noise  from it when HV is turned off......
> Maybe the Cut-Off voltage is to low? Have the PA at home and will try to work this out, otherwise I have to use my 250 watt SSPA next weekend........
> 
> 73 de Viggo  LA9NEA
> 
> LA9NEA 23 cm EME set up:
> Icom 756 pro II
> TR1296H trv Kuhne
> 6 x 7289 ring PA ,500 watt,
> MKU 13200B(spare PA) 250 watt SSPA,
> 5.3 meter dish,
> VE4MA Feed
> 1.stage preamp.Cavity NE32484 0.28 dB
> 2.stage Kuhne  MGF 4953A 0.4 dB
> JO59dx
> Autotracking by W2DRZ,
> VK3UM tracking at screen.
> _______________________________________________
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