Batboard

Hi guys and Happy New Year!

I have a few VHF system sabers that all perform very well. However, one of these radios just does not have the sensitivity that the others do. No access to test equipment-but in comparing it to the other radios and a scanner on the same freqs it's just not up to snuff... any thoughts or ideas?

Also, are the modules the same part #'s as regular Sabers?

Thanks,

Rich

Rich:

All Sabers and Systems models take the same parts, respective of their band split, there is no difference.

You may have one radio with a Xtal filter(U5) that is not proper for the band split you have programmed into the radio, this will cause decreased sensitivity, as will a defective U4, receiver module.

Other modules you may wish to look at, are the 2-pole filter and the F.D.S(filter/detector/switch), which switches TX and RX paths and acts like a harmonic filter as well for the transmitter.

If the F.D.S, as well as the 2-pole filter are of the incorrect band split, you will also notice a decreased level of sensitivity, as well as an increase in impedance due to the filter being outside of the operating frequency range, and this will affect both transmit and receive, although you will probably not notice the decrease on transmit, it will affect reception though.

Always make certain you use the proper module numbers for the band split you have your radio programmed in, like 136-150.8 or 146-164, that way, you will obtain peak performance.

You can also go into the service menu and check the squelch levels, which also directly affect reception as well, not to mention transmitted power and TX audio (mic gain).

Mic. gain is a function of the VCO modulation adjustment in the standard Sabers.

You should never have to adjust the reference modulation unless you have higher than acceptable PL deviation, both tone and digital.

Setting the reference too high will cause falsing and tone problems, but it's always best to check both tone and DPL levels with a proper deviation meter/service monitor.

I sometimes had bad solder joints on SMD capacitors in the module including the switching of RX and TX path. Resoldering them fixed; had this in VHF mid band Sabers, but maybe only because those are more common in Germany than VHF 2m Sabers.

AEC wrote:Rich:

All Sabers and Systems models take the same parts, respective of their band split, there is no difference.

You may have one radio with a Xtal filter(U5) that is not proper for the band split you have programmed into the radio, this will cause decreased sensitivity, as will a defective U4, receiver module.

Other modules you may wish to look at, are the 2-pole filter and the F.D.S(filter/detector/switch), which switches TX and RX paths and acts like a harmonic filter as well for the transmitter.

If the F.D.S, as well as the 2-pole filter are of the incorrect band split, you will also notice a decreased level of sensitivity, as well as an increase in impedance due to the filter being outside of the operating frequency range, and this will affect both transmit and receive, although you will probably not notice the decrease on transmit, it will affect reception though.

Always make certain you use the proper module numbers for the band split you have your radio programmed in, like 136-150.8 or 146-164, that way, you will obtain peak performance.

You can also go into the service menu and check the squelch levels, which also directly affect reception as well, not to mention transmitted power and TX audio (mic gain).

Mic. gain is a function of the VCO modulation adjustment in the standard Sabers.

You should never have to adjust the reference modulation unless you have higher than acceptable PL deviation, both tone and digital.

Setting the reference too high will cause falsing and tone problems, but it's always best to check both tone and DPL levels with a proper deviation meter/service monitor.

The only thing is... don't the system Sabers cover the whole band, not like the older Sabers which were divided into splits? When I read the radio, it comes up 148-174 under the model #.

I adjusted the squelch levels nice and loose-I'm in the sticks here!

I did open the radio-it's in such pristine shape there aren't even any figerprints on the frame, etc. This is one of the surplused gov't. radios so I'm aware of the potential for winding up with a high split but this one is not.

I'll have to wait and wait 'till I get another 'known good' to swap modules with... don't wanna pull apart other, perfectly working radios.

Thanks for the info though-haven't fooled with any Sabers since 1999 so I'm getting back up to speed.

Rich

Systems Sabers and standard Sabers both share common modules, and to my knowledge, the Sys Saber doesn't cover the whole VHF band (officially) without some degree of performance loss at some points. Most of the those Fed System Sabers showing up are either low split or high splits, at least the ones I've come across on Ebay fall into that category.

MTS2000des wrote:Systems Sabers and standard Sabers both share common modules, and to my knowledge, the Sys Saber doesn't cover the whole VHF band (officially) without some degree of performance loss at some points. Most of the those Fed System Sabers showing up are either low split or high splits, at least the ones I've come across on Ebay fall into that category.

As far as I know there are dozens of different modules, and there are some with wider bandwidth than others. My Systems Sabers seem to offer full performance from 148 up to 174, without any problems. Are there some official Mot documents still availabe to show what is fact? I would be highly interested in all stuff about the Systems Sabers as PDFs, flyers, manuals, service manuals...