Zetron 48MAX problem

[KF4LZA]

I have wired it right to a MSF5000 CXB station. It will pass PL users encode/decode and it will decode dpl without a problem but cannot get the radios to open squelch from the dpl being transmitted on the transmitter. I have the 33kohm resistor on the leg going to the direct modulation IC. like i said PL is no problem I cant get the DPL tone to open the radio's in the field. I have adjusted the pots on the zetron that handle tone output with no avial. anybody know anything else to try?

[d119]

Have you tried looking at the stations deviation settings with regards to the EEPOTS in the service menu?

[RKG]

Whenever I have a receive qualification issue using DPL, my first try is to invert. It seems that none of the manufacturers agree on the definition of which way is "normal" and which is "inverted." In fact, I've found that different products from the same manufacturer will differ in this regard.

[KF4LZA]

I have tried the invert function with no luck, i tried adjusting the station transmitter epot deviation control also with no such luck. I am ready to dump the zetron maybe, i don't know what else to try.

[RKG]

The Zetron external controllers (38A, 38Max, 48 and 48Max) are the best there are. The problem is in programming or wiring.

[KF4LZA]

Ok well then is there a better way to wire it to a digital CXB MSF5000 than the way that the Zetron manual states?

[RKG]

Can't say; never done it. (Bernie?)

[Vercomm]

If you send zetron a quick email they usually get back to you right away. I think I have some applications notes from them on connecting their devices to msf5000. There is a difference in the way they connect between the analogue and digital version. Is the wiring diagram that's in the manual for the digital or analogue station. i will look tomorrow on my laptop to see if I still have the application notes.

[KF4LZA]

they sent me the whole manual on pdf and i have both the analog and digital hookup diagrams. I followed the digital one to the T. I am passing PL signal to the direct modulation IC on the MSF and the radios do not hear the DPL on the transmitter output no matter what I do! They hear the PL audio when its encoding PL just fine.

[RKG]

Problems with encoding DPL are sometimes attributable to waveform shape and symmetry. I'm not an expert with MSF, but later stations had a section in their Maintenance Manuals re: checking and adjusting waveform shape.

[KF4LZA]

but wouldnt that be involving the waceform and shape of the dpl coming out from the zetron not the MSF? The station is not making the DPL the zetron is.

[RKG]

Don't ask me too many follow ups, but no, it has to do with the transmitter. If not properly aligned, it can skew the perfect DPL shape coming out of the Zetron to the point where a DPL decoder will not recognize it.

[Will]

Ok well then is there a better way to wire it to a digital CXB MSF5000 than the way that the Zetron manual states?

Yes, at least on the "analog" MSF.

The PL AND DPL signal must be on a seperate line and goes to the mix point, after the IDC, just before the VCO. I use a 10k to 47k resistor to isolate the PL/DPL line from the Zetron.
The TX audio goes into the modulation/IDC stage so the Deviation never goes over the xK dev limit.. Just follow the Mic line thru a few analog gates to the input of the IDC (AKA Deviation limiter/amplifier/roll-of filter) stage/IC. Again I used a series resistor to reduce noise pickup and help set the levels easier.

[KF4LZA]

everything is perfect now. I had to ground the shields on the PL/DPL line better.