Thursday, February 26, 2015

ZF1AM 1854KhZ

LSB ZF2AM heard very weak here early morning  Also PW0F was on topband  but not heard
better in south / east EU
 but precisely  1854kHz  is covered by some new s.m.Power? QRM I have direction west to direction the village at 1.2 km
The directivity of the Beverage is clearly seen on that QRM  it is almost gone when switched to East.
The QRM frequency is slightly moving around. It is about 5kHz wide only
Not able to find out yet where this new one is coming from.

Germanium diodes received from Mini in the box
1N34  and  1N60 type  150 pieces 4$ only received
 Tested  at 431MHz  with my EME UHF directional coupler
the BNC ports have calibrated attenuation I had 2 diode detectors one of them is broken.
Tried to repair by inserting an pin contact diode into the BNC but overheated the diode
is not easy to mount into a BNC connector.
 The diode still works but derated it gives 20% less detected Voltage.
That diode is unknown junkbox  type Ge -pin  showing "0" Pf  and 0.4V  barrier at may tester

I found a much easier way using BNC-RCA adapter
In the audio RCA it is easy to mount the diode without overheating using a pincer as heat sink.
The original EME diode head gives just over 2V  at 431MHz 10W level forward port and backward 0.2V
RCA type BNC are not designed for UHF but I got same result 2V output slightly less then the original.
The 1N34 has about the size of a 1N4148 while the unknown GE-pin type i have destroyed is twice as big
but smaller then the antique OA95 types
It tested as 0pF  0.4V  thats what you need 0pF. the 1N34 1N60 seem to have slight higher parasitic capacitance 1-2pF  but up to 430MHz they work well  possible higher I could not test that.




EME precision directional coupler

the easy way using RCA adapter type BNC


  the 1N60p    the unknown now destroyed one showed 0pF at 405mV
Noticed that the detection Voltage drops about 10mV /sec it needs temperature compensation for accurate measuring.
SWR/PWR bridge for 630m  works also at 50MHz

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