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| Replacement for the PM9610 Prescaler for Philips PM6654 High precision Counter |
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| SaabFAN:
I've designed a new version. It still uses the MC12095 / 12093 Prescaler-Chips, but also adds a Power-Meter and an ADC to read the voltage coming from the chip measuring the RF-Power (about 36dB down from the actual input-power). I have bought 5 boards and there are now 3 left, so if someone wants to get one of those, please PM me. :) Attached are pictures of the new boards. |
| FransW:
The original 1.5 GHz input board had it's input part shielded with a ni-plated brass box, soldered over the pre-scaler part. Frans |
| SaabFAN:
The shields on the original units were most likely there because Philips had to build the RF-Amp with discrete components with the technology available. For the first Version they even had to use through hole-components. With the Amp implemented as a single MMIC, I don't think its necessary to put any shield on the board. Especially given the fact basically nothing else inside the counter is shielded :) I have had some time to measure the highest possible frequency at -20 dBm this weekend: 2070 MHz. The Signal-Source I used was my DIY Signal Generator, which uses a ADF4351 for anything higher than 400 MHz. At lower frequencies (1.5 GHz), I can go as low as -29 dBm. The lowest frequency the board was able to count was 8 MHz btw. Higher amplification on the board might help with these performance-figures, but might also cause other signals to become too strong - Might be worth some investigation, but for the moment I'm pretty happy with the results :) |
| SaabFAN:
I have updated the Boards to Mk. II Rev. A Changes: - Replaced T-Junction at output of RF-Amplifier with Resistive Splitter - Added second RF-Amplifier to compensate for losses in Resistive Splitter and increase sensitivity - Replaced the MC12095 Prescalers with MC100EL33 (MC10EL33, SY10EL33 and SY100EL33 fit also), as these parts are listed as "Active" by the manufacturers - Replaced the NE5532 with a LM258 OpAmp in SOIC-Package to save space - Schottky-Diodes of the automatic limiter-circuit replaced by BAT15-04 (2 Diodes in one package) - Removed unnecessary Filters (High Pass at input of first Amplifier and Notch-Filter for the Detector) - Replaced Zener-Diode for the negative supply with LM79L05 - New Board-Layout with larger and less Vias, as well as additional mounting-holes for a standoff (this standoff can be glued to the Mainboard, which makes mounting easier) - Removed RF Power-Measurement features (caused problems) The additional amplifier, together with the new Prescalers should improve sensitivity (hopefully not so much that noise is being counted :) ) and increase the measurement-range up to 2.5 GHz (currently the counter loses the signal at about 2.1 GHz but if I remember correctly, the normal inputs could count up to 160 MHz which gives a max Frequency of 160 x 16 = 2560 MHz). Attached is a 3D-Rendering of the new board. I tried to avoid having to route stuff on the bottom side, but a few traces had to go down there. Undivided RF-Path is undisturbed though. I again went for a Coplanar waveguide-design but with larger Vias this time. |
| geostep:
SaabFAN, Thanks for the continuing effort improving your PM9610 replacement! I'm looking forward to trying this out on my recently acquired PM6652. - George |
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