Unit assembly   - second batch.....

The converter was designed to fit within an Eddystone 29830-P die-cast housing, which is 120x95x30mm. This is available through RadioSpares (343899), Maplin (N90BQ) or Farnell (301530).

   box end                         

drilling template

A drilling template, in pdf format is available here.

(click on either drawing for full size image)



Standard build does not include Ref I/P

Die-cast box
RadioSpares 343899 etc
Supply socket 2.5mm
Maplin JK09L
Pillars M2.6  (6 off)

Countersunk screws  M2.5 x 6  (6 off)
For pillars
Nuts M2.5  (8 off)

Plastic clip for LNB

Pan head screws M2.5x 10  (2 off)
 For plastic clip
Steel washer M3  (2 off)
 For plastic clip
M2.5 nut (4 off)
 For plastic clip
Input coax (75mm RG178)  For x23 multiplier

This is the easiest section...         
Assemby is straightforward – fit the pillars to the box first, then the 450 MHz multiplier and the mixer pcbs. For the moment, leave the x23 multiplier unfitted.

Make up the dc leads to the supply socket and fit to the box (two red leads, one 100mm long, the other145mm and a black lead 65mm long). Solder the negative lead to the 450 MHz multiplier pcb as shown in the opening picture (rh side) – just use one of the ground holes provided for the 450 MHz O/P connector (which is never fitted).

The two positive leads can be pushed into the +ve supply holes on the two pcbs.

Solder the coax leads to the mixer pcb. The one with the white sleeving goes to ‘LNB’, and the one with blue sleeving to ‘IF O/P’. Solder the inner wire into the appropriate hole first, then the screen to the groundplane, taking note from the picture of which direction the coax has to depart from the board. Finally fit the socket end of the cables to the appropriate housing holes. With a finger on the connector rear, tighten up the nut using a 5/16” spanner. Tighten really well.

X23 multiplier pcb

If not already fitted,screw the aluminium bracket, shown opposite,  to the pcb using 2  M2.5 x 6 pan head
If making this bracket yourself, use a 40mm length of 1/4 inch square section stock, drilled 2.3mm as
shown and tap M2.5 mm. The shorter spacing is 20mm, whilst the longer is 30mm.

x23 bracket
Just sit the board assembly into the unit housing, but don’t screw the fixing countersunk screws in yet. Bend the quick-form coax output lead to shape, and fix the sma connector to the box (fitting to the hole nearest the corner of the housing), Again, tighten up the nut using a 5/16” spanner.

Now solder the ptfe clad input coax to the 450 MHz multplier pcb, soldering the inner connector first.

The x23 multiplier can now be aligned prior to screwing the board firmly into the housing.

x23 multiplier Board alignment

The pipe cap cavities have already been pre-tuned, and should only require a final tweak at this stage.

Simply apply 12v to the power socket and feed the x23 multiplier output into a spectrum analyser, however, you may need to use the analyser on its most sensitive setting, and with the bandwidth reduced down to the minimum practical value.

Peak the output by making small adjustments of a fraction of a turn on both cavity screws. With both cavities peaked, the output should be about -40 dBm.

Once aligned (and the lock nuts tightened), the board assemby can be screwed into the main housing.

If making your own pipe cap assemblies, try to pre-tune them also prior to soldering. It is easy to make a jig with two pobes projecting through by 1mm or so Tune for a peak with the cavity held down to the jig by hand.
cavity tuning



Mixer alignment

If the accompanying LNB is not available, use a signal generator tuned to 618 MHz to feed a signal into the ‘618 MHz LNB IF I/P’ port (be aware that there there will be 12v on this pin, so either fit a dc block or be sure that the generator is itself fitted with a dc block). With a spectrum analyser connected to the ’18 MHz IF O/P’ port, tune L51 (issue 1 pcb legend falsely states ‘L50’) for maximum signal at 618 Mhz.

If an LNB is fitted to the converter, either tune L51 for maximum noise out of a receiver tuned to 18 MHz connected to the ’18 MHz IF O/P’ port, or apply a signal to the LNB at 10 368.000 MHz and adjust L51 for maximum signal at 18 MHz.

Note: The 10 MHz TCXOs used in this converter tend to be 25 – 50 KHz high in their initial frequency when multiplied up to 10 GHz.

LNB fixing screws

If an LNB is going to be fitted as part of the unit assembly, fit the two M2.5 x 10 provided through the two non countersunk holes. Note that one nut per screw is used to secure the screw to the box – the 40mm mounting clip is a snug fit over this nut. The clip is secured using the second nut and the M3 washer
LNB clip