Products > Test Equipment
Replacement for the PM9610 Prescaler for Philips PM6654 High precision Counter
SaabFAN:
No idea what Connector BU302 / BU02 does.
My counter has no holes in the mainboard at that location and the service-manual doesn't mention anything that would connect to this connector and the diode located there.
It might be possible that the PM9610 was used in other counters as well, though, and those needed that connector to enable the high frequency channel.
To activate channel C on the PM6652 and PM6654, the pins 5 and 6 on connector BU107 have to be connected. That sets the configuration-bit for the RF-Option.
Btw. when testing the ADF4351 at different frequencies, I discovered that my board is able to prescale a 2.4GHz signal at 0dBm - But there's a notch around 1.6GHz (displayed frequency jumps all over the place) and 3GHz is too much (counter only displays "0."
david69:
It would be like this scheme? I have several MiniCircuits
MAR6, or ERA3 should be working up 2GHz, the divider
MC12095 is easy to buy on Ebay :) This scheme would
be produced noice and wrong counter`s display, but I think in cause "right signal" the counter should be displayed right value :) Thanks and Happy Easter
SaabFAN:
Yes, in the absence of a strong enough signal, the counter "counts" the noise. Also the Prescalers tend to self-oscillate at a certain frequency.
That's why the detector-circuit with the OpAmp is in there. It turns off the prescalers if the input-signal isn't strong enough, preventing any signal from appearing at the output.
I have included the detector-circuit on by board, but at the moment I've turned down the sensitivity of the circuit so the prescalers are always on. In essence it works like the circuit you drew up.
Important is a 30dB gain at the input to be able to count a 10mVrms signal and the limiter to go up to 12Vrms without blowing the amplifier.
Edit: You need a termination-resistor between the MMIC and the Prescaler. It doesn't have a 50 Ohm Input-Impedance, so no termination will create reflections and all kinds of trouble. The Terminator must be on its own segment of the signal-path with DC-Blocks in both directions. You cannot connect it directly to the input-pin of the prescaler. It would eat up the bias-voltage at that pin and make the ECL-Circuit inside Prescaler "deaf".
Also keep in mind to have a solid ground-plane underneath the chip, or it WILL become an oscillator (see earlier posts).
david69:
My idea is use RF detektor LT5538 with comparator, where You
can set needed GAIN,
SaabFAN:
Why use such an expensive chip when you can do the same with a simple diode? You don't want to measure the RF-Voltage accurately over a huge dB-Range. You just need a rough value for the comparator to turn the outputs on or off.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version