projekte:3cmcompacttrv:start
Unterschiede
Hier werden die Unterschiede zwischen zwei Versionen angezeigt.
Beide Seiten der vorigen RevisionVorhergehende ÜberarbeitungNächste Überarbeitung | Vorhergehende Überarbeitung | ||
projekte:3cmcompacttrv:start [2022/03/20 16:54] – [TX IF Filter] yc | projekte:3cmcompacttrv:start [2022/05/23 18:12] (aktuell) – [Transverter PCB] thasti | ||
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{{: | {{: | ||
- | First all the details of the modules were reverse engineered(documented [[projekte: | + | schematics: {{ :projekte: |
+ | project files: [[https:// | ||
- | {{:projekte: | + | First all the details of the modules were reverse engineered(documented [[projekte: |
===== Concept ===== | ===== Concept ===== | ||
Zeile 19: | Zeile 20: | ||
===== Modifications ===== | ===== Modifications ===== | ||
- | ==== TX Baseband Filters | + | ==== Transverter PCB ==== |
- | The original lowpass has a cutoff frequency of ~12 MHz, which is replaced by a 3rd order 60 MHz filter. | + | The transverter PCB is visible on the top of the unit. To perform the modifications shown below, its milled RF shield needs to be removed. For this, only the screws visible on top of the RF shield need to be removed, the PCB itself can remain screwed to the base of the unit. |
+ | |||
+ | === TX Baseband Filters === | ||
+ | The original lowpass has a cutoff frequency of ~12 MHz, which is replaced by a 3rd order 60 MHz filter. | ||
{{: | {{: | ||
- | ==== TX IF Filter | + | |
- | The original ceramic filter is removed and the attenuators are replaced by 0R resistors. | + | === RX IF Filter === |
+ | The original 70 MHz IF filter is not used and the signal path is switched to the second not populated filter footprint. A pcb with a 3rd order 50 MHz bandpass filter was made and fits on this footprint. | ||
+ | |||
+ | {{: | ||
+ | |||
+ | schematics: {{ : | ||
+ | project files: [[https:// | ||
+ | errata: | ||
+ | * PCB pinout is flipped vertically, hence short wires are required to connect RF path to coupling capacitors on the PCB. | ||
+ | |||
+ | === TX IF Filter === | ||
+ | The original ceramic filter is removed and the attenuators are replaced by 0R resistors. | ||
{{: | {{: | ||
- | In theory image rejection by the quadrature mixer can be tuned to -60 dBc or better | + | In theory image rejection by the quadrature mixer can be tuned to -60 dBc or better, however |
{{: | {{: | ||
Zeile 33: | Zeile 50: | ||
errata: | errata: | ||
* MMCX instead of MCX used, fix in next revision | * MMCX instead of MCX used, fix in next revision | ||
- | ==== PA Power Supply | + | |
+ | ==== RF Board ==== | ||
+ | The RF board is the lower, large PCB enclosed between the two main halves of the body. The RF board is exposed simply by removing the six large screws on the bottom of the unit. The thermal/ | ||
+ | |||
+ | === PA Power Supply === | ||
The 48V DC/DC module and TR4 are removed. A IRLML6402 is placed upside down on the TR4 footprint as shown in the picture. With two additional wires the drain voltage is switched on when the negative gate voltage is there. | The 48V DC/DC module and TR4 are removed. A IRLML6402 is placed upside down on the TR4 footprint as shown in the picture. With two additional wires the drain voltage is switched on when the negative gate voltage is there. | ||
{{: | {{: | ||
- | ==== RX IF Filter ==== | ||
- | The original 70 MHz IF filter is not used and the signal path is switched to the second not populated filter footprint. A pcb with a 3rd order 50 MHz bandpass filter was made and fits on this footprint. | ||
- | {{: | ||
- | |||
- | schematics: {{ : | ||
- | project files: [[https:// |
projekte/3cmcompacttrv/start.txt · Zuletzt geändert: 2022/05/23 18:12 von thasti