|Contents:||Introduction||Principle of operation||Planning||Realisation||Pictures||Reception reports|
The 10GHZ beacon PI7GOE has been mentioned in various beacon lists for many years.
Yet, the beacon PI7GOE is still not QRV. But this will change soon:|
Some SHF-enthousiasts within our Radio Club have set up a plan to become active on 10GHZ with narrowband SSB / CW. We'll start with building and operating the beacon PI7GOE at 10368.075MHz. This beacon is eventually going to be located at the Churchtower in the town Kapelle (locator JO11XL), co-located with the 2m repeater PI3GOE at 145.725/145.125MHz.
Further, as an initiative of the Radio Club, a joint transverter building-project will be started with the intention to stimulate activity on 10GHZ in our province Zeeland. More information about this 10GHz transverter project will be given during the monthly Veron A33 meeting on october 30 1998, in the Radio Club (see main page).
|Principle of operation|
The principle of operation of the 3cm beacon PI7GOE is (for the time being):
Local oscillator: G4DDK004 2-2.6GHZ LO source: Crystal oscillator on 108.00078 Mhz,
output: 10mW at 2592.01875 MHz
2.5 to 10GHz multiplier G3WDG001:
In this module the 2.592MHZ LO signal is multiplied by 4 to
the desired transmitting frequency of 10368.075MHz. Output power is approx. 100-150mW.
1Watt 10GHz Power Amplifier G3WDG007:
Initially we don't have plans to build this module and use it for PI7GOE as
we're still looking for a sponsor for this module or at least for the expensive MGF2430A power GaAs FET.
Slotted waveguide antenna: The signal of the x4 multiplier module
is fed to waveguide (WR90) via a SMA-Waveguide transition directly at the
multiplier output connector.
The piece of waveguide is acting as a omni-directional antenna.
Beacon CW keyer: For identification purposes of the beacon,
OM. Willem PA7WLH (ex PE1FYO) has volunteered to develop a CW-keyer. Altough many designs do exist,
this keyer is built in a 87C51 microcontroller, the program (firmware) for the keyer
is also written by Willem. More information and the schematics of the keyer can be found
at his website
The (adjusted) time schedule of this project is:
september 4-18 1998: Functional design of the Beacon CW keyer.
|(Problems encountered during) realisation|
October 1998: The oscillator signal of the 2.5GHz LO module is not stable enough, it sounds jabberish/howling
when listened to the 12th harmonic on 1296.0093MHz, with a 23cm SSB receiver.|
Listen to a recording of the signal in WAV format.
After discussing this problem with Sam G4DDK, several parts (such as the crystal) have been checked.
Eventually an unstable carbon resistor R4 (470ohm) across the coil L1 appeared to cause some of the instability. After replacing this resistor with a metalfilm one, the signal sounds more stable (but isn't perfect yet).
November 1 1998: Replaced the 2 BFY90 transistors (TR1 and TR2) in the oscillator and buffer circuit bij new ones. Sam G4DDK advised to mount the metal-case almost direct on the PCB with leads as short as possible, and the cases soldered to the groundplane of the PCB. Unfortunately this still not results in improvement of the signal stability.
November 4 1998: Tried another crystal (106.5MHz) in the oscillator circuit. The 12th harmonic (on 1278MHz) sounds much more stable. So my conclusion is that the original 108.00078MHz crystal must be causing the instability. I have sent Email to the crystal supplier with a complaint about the bad crystal. We're awaiting his reaction...
December 11 1998: An envelope containing a new 108.00078MHz crystal was in my mailbox today.
Unfortunately I had no time to test it right away - Today is my son Julian's first birthday!
January 2 1999: Because of financial advantage, I got the opportunity to invest in a piece of
measuring equipment that is much desired in our hobby: I've purchased a (2nd hand) spectrumanalyser, suitable up to 22GHz.
Now the signal of the 2.5GHz LO-module and later on the multiplier module can be analysed really good.
(Pictures of this will follow).
Your reception reports of the beacon PI7GOE are welcome!|
PSE QSL PI7GOE via PI4ZLD, Region 33 (via the Dutch Qsl Bureau or direct to PI4ZLD).
You may also contact us by submitting the comment form below.
Reception reports received so far during test at location JO11TL, Power=30mW, antenna at 12m asl:
date time call locator QRG RST 19990402 20.00Z PI4ZLD JO11WM .075 519 - 529 19990402 21.00Z PA0WWM JO22FE .055 519 - 549 19990403 09.00Z PA3DYS JO21JO .059 53RS 19990405 10.20Z PA0WWM JO22FE .065 52RS QTF 220°Reception reports received so far during test at location JO11TL, Power=80mW, antenna at 12m asl:
1990410 16.45Z PA0WWM JO22FE .067 52RS QTF 220° - 195° date time call locator QRG RST
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Eddy van Loo , PE9GHZ, ex.PE1CIG