DG7YBN / 432 MHz EME Station
  Last Update Dec. 06th 2014




.......


On this website I give a little overview on my 432 MHZ EME efforts. The setting is ... I do not intend to take a
serious amount of cash and buy me a super station but rather see how to get along with sensibly chosen componets
and a fine line up of either self made or second hand equipment that needs a hand. Which is probably close to self
building then. Because one at least has to understand what is to be repaired. Neither do I have endless antenna
space nor time for my amateur radio hobby.

After all, who finishes with a high rank in the Dubus or ARRL EME contest:
... SSB Electronic, Beko, Lunar-Link and m2 or InnovAntennas OR you?

Current array (until I have four own GTV designs built). This was my first 432 MHz array. I bought it as a late
teenager way back in the early 1980s. With the starting signal in early 2014 - the purchase of an 'abandoned'
standby 432 MHz GS35b Cavity PA of DF0MU I began building this station around it. So I thought about using
my veteran 432 MHz DL6WU Konni F20 array as an interim solution (simulated gain is 23.4 dBi).

EME? ... is sending a radio signal from earth to the moon, using it as a reflector, so that another station can
receive than signal down on earth. Earth -> Moon -> Earth = EME. Hence the enourmous distance of 2 x 384,400 km
the signal has to travel there is a path loss of 250 dB roughly and a time delay of 2 seconds.


Image: © Dr. Tanja Kurzenknabe





Station




Array (Cheap Tricks Part 2... see Part 1 - modified Tonna 19 ele. click )



This is a 4 x 20 ele. DL6WU design sold as 'F20' by Co. Konni-Antennen, electrical length just under 6 wl. (4.1 m) with
modified Balun and D1 by DG7YBN. With the experience gained in recent years I removed the poor PCB and low quality
coax balun and replaced that by a balun made from RG142 PTFE with direct connections. Looking up this DL6WU design
in the 432 MHz VE7BQH G/T table click we find it not being bad at all.
What is sensitive is the way the dipole box and balun was produced by Konni-Antennnen in the early 80ths.

See the old and new balun

 

A length of 2.00 m of RG213mil with even 30 years old N-connectors leades from each DE to a 1/4 wave splitter made from
brass + copper (UKW-Berichte? / looks like the ones sold by WiMo). Patch coax from splitter to coax relay is approx. 1.3 m
of H100. To overcome the stiffness problem of the H100 I arranged a wide bow around the elev. axis of the rotor.


TRX



I am using an ordinary Yeasu FT-736R. No extras fitted, no modification done.
Frequency stability is alright as long as I start it up about 15 minutes before I want do start operation.
The RX is quite deaf on 70 cm, I am thinking about building a second stage high IP Preamp and bandpass filter
to follow the mast mounted LNA.


Coax Relay and LNA



The mast switch box holds a RelComm RDL SR012 (insertion loss .02 dB / port isolation > 90 dB @ 432 MHz) and a
directly connected tgn-technology ULNA 3013 EME that came with a measurement protocol stating an NF of .28 dB.
For details on that switchbox click here.

From here to shack I use separate RX and TX coaxes. RX is approx 28 m of RG213, TX is 24 m
of 5/8 Flexwell with 7/16 connectors patched with a 0.5 m of RG213 from its 7/16 to N and to get it into the switch
box properly. A larger switch box with 3 x 7/16 coax relay suitable for direct connection and splitter with 7/16
bushing is planned. An Andrews Heliax 5/8 patch coax is waiting already


Elevation & Moon Tracking



Rotor is a common Yaesu G-5500 combination. Moon tracking is by hand. I have a 2.4 GHz link camera installed in
a plastic drain tube with cross lines made from flower binding wire. That gives me an additional noise floor when
on of 1 dB approx. and works find with the HPBW (12 degr. approx.) of that bay with one well known big disadvantage:
Even though IR sensitive moon is 'gone' when behind heavy clouds ... , not to mention daylight .. hi ..


Power Amplifier



This is a GS35b PA cavity design (produce of DJ3FI). Due to the high Q of that anode cavity its 'low power'
amplification gain is in excess of 13.5 dB so that the driving power of my FT736R lets me almost explore legal limit
power here ( > 600 W). Which is way enough for the N-connectors up on the pole.

An LDMOS driver might follow when a bigger switch box is mounted with an all 7/16 connectors coax relay.

Coax Feedlines 7/16 Connectors



TX; 5/8 in Flexwell and 1/2 in Andrews patch coax with 7/16 connectors in shack
(connectors gifted by Oliver, DL2ARD of DL0GTH es Helmut, DG9YIH of DF0MU tnx!)






Sun Noise




With the EME Calc by Dough, VK3UM my RX-System as described above should give a sun noise of 10.5 dB @ sfi = 146✶.
I measure 9..10 dB in my quite noisy location.

(✶) sfi is a measure for solar flux (density) at 10.7 cm or 2.8 GHz. This number is of limited use for quantifying
the actual flux on 432 or 144 MHz. In smart programs like the VK3UM EME Calculator solar flux numbers for a span of frequencies
are gathered and lined up with an algorithm to derive relatively good calculated numbers for the amateur bands. In my article

Notes on VHF/UHF Antenna G/T, Dubus 2/2012 & Dubus Technik XII

I show that in explicite way with sfi vs. frequency charts added.





RX wise



First 'SWL' activies

.. even with crude soundcard in/output rates ...

• 2014-04-12: Received NC1I as special call W1AW/1 (48 rear mounted 15 ele. Yagis + QRO) with up to -6 dB and very clear speaker copy
  Link to .wav sound page click , mind that this NOT through a narrow CW filter but full SSB 2.7 kHz audio
  Here is a link to OK1TEH's 432 MHz EME Stations gallery click



• 2014-04-12: Received HB9Q (15.3 m dish + 2kW PA) with -12 .. -10 dB in bad moon position with beam scratching house roof
  Here is a link to OK1TEH's 432 MHz EME Stations gallery click



• 2014-11-07: Received OK1DFC, Zdenek (10 m dish + 1.5kW PA) with -14 .. -11 dB



• ARRL EME Contest, Nov. 8/9th 2014: Received quick QSO between HB9Q (10 m dish + 1.5kW PA) and UA3PTW (20 x 15 ele. mod. DJ9BV)



• ARRL EME Contest, Nov. 8/9th 2014: Received DL7APV CQing (16 x 13wl DJ9BV) with up to -7 dB



• ARRL EME Contest, Nov. 8/9th 2014: Received SM2A CQing (4 x 32 ele. - 13wl)



• ARRL EME Contest, Nov. 8/9th 2014: and a little pile up calling JE1TNL - UT5DL (8 x 7.7 wl DJ9BV, 600 W ?)





I am not fully QRV yet. The sequencer is not complete. Stay tuned ...





73, Hartmut, DG7YBN



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