HP 5254A/B/C FREQUENCY CONVERTER MODIFICATIONS

For use as… HI-Q TUNEABLE BANDPASS FILTERHARMONIC GENERATOR / FREQUENCY MULTIPLIER

Frequency range: 300 MHz to 3000 MHz

Harmonic generation: Cavity filter selects one harmonic every 50 MHz .Level: -30 dBm nominal, Adjacent harmonic suppression: ~ 30 dBUse to magnify phase noise on low noise 10 MHz clocks, since

it adds little noise of its own.Added phase noise = 20 * log(N) where N is the frequency multiplication factor

Jacques AudetVE2AZXve2azx@amsat.org

BLOC DIAGRAM

X5 MULTIPLIER HARMONICGENERATOR

TUNEABLECAVITY

Couplingloop

50 MHzExternallySupplied10 MHz

Selects one harmonic of the 50 MHz comb,from 300 MHz to 3000 MHz. Level: ~ -30 dBmAdjacent harmonics are suppressed ~30 dB

HARMONIC GENERATOR PCBRG-174 coaxis brought to thefront of HP 5254A

HARMONIC GENERATOR PCB

GND

+13V-15V

10 MHz

Keep the harmonic generator PCB. The other PCB assemblies may be discarded.

This heat sinkwas added

Underside of harmonic generator PCB,showing loop and step recovery diode

This is the cavity output coaxthat is connected to the front BNC

In the harmonic generator configuration, the blue edge connector applies power and 10 MHz reference to the multiplier assembly / harmonicgenerator pcb, located on top. The pcb is held in place by the two screws on each side of the loop.The other modules are discarded.

Filter IN / OUT orHarmonic GeneratorOutput.

For bandpass filter configuration:Remove the harmonic generator PCB and add loop.

Addedpower supplyfor harmonicgenerator

Harmonic generator Configuration

Power Supply and 10 MHz Connections on the 50 pin rear connectoras required in the harmonic generator configuration.The 10 MHz level should be +5 to +10 dBm.This connector has been discarded. Power and 10 MHz is now brought directly to the harmonic generator PCB, via a 2x6 pin double side connector.

Harmonic generator Configuration

Comparative Phase Noise Tests1 GHz out vs 10 MHz Time Base

Note Blue curve represents the SpectrumAnalyzer (HP 70000) residual phase noise

Front ofmodule

Front ofmodule

Bandpass FilterConfiguration

BNC and SMA loops

Note the loop alignement w/rto front of module

Scale in cm

Scale in cm

0

2

4

6

8

10

12

14

16

0 500 1000 1500 2000 2500 3000

Frequency MHz

Loss

dB

SMA loopBNC loop

Filte

r

BANDPASS FILTER

CHARACTERIZATION

0.00

2.00

4.00

6.00

8.0010.00

12.00

14.00

16.00

18.00

0 500 1000 1500 2000 2500 3000

Frequency MHz

-3 d

B B

W (M

Hz) BNC loop BW

SMA loop BW

BNC and SMA loops

Filter at 1000 MHz

OverallResponse

BNCloop

Filter at 300 MHz

Filter at 2000 MHz

Filter at 3000 MHz

OverallResponse

SMAloop

Filter at 1000 MHz

Filter at 300 MHz

Filter at 2000 MHz

Filter at 3000 MHz

HP 5254A/B/C FREQUENCY CONVERTER – BLOCK DIAGRAM

HP 5254A/B/C FREQUENCY CONVERTER – SCHEMATIC

HP 5254A/B/C FREQUENCY CONVERTER – PART LOCATION