Stridsberg MCA204M Multicoupler Problem

[timkilbride]

I bought a Stridsberg MCA204M Multicoupler here off RR. I finally got it hooked up today. It doesn't work as far as I can tell. My HT1250(not hooked up to the multicoupler) is picking up more then the CDM1250(VHF) which is hooked up to the multicoupler. The antenna(VHF) is located on the roof that goes to the multicoupler. The power supply that it came with is from some sort of Uniden scanner. The output is 13.8V, the muliticoupler requires 12V. I did a continuity test from the antenna input to the J1-J4 outputs and nothing. Both powered and un-powered. Any ideas? I'm guessing something is burned/blown internally on the multicoupler?

Tim K.

 

[gmclam]

The only real way you can check a multicoupler is to measure the signal level on its input and each of its outputs with an RF meter or spectrum analyzer. You will not see "continuity" with a DC ohm meter.

As far as power goes, if you are providing 13.8 volts regulated you are probably OK. Most devices can handle a 10% overage and/or have internal regulation for the actual circuit voltages.

You can't really use a scanner to tell what is happening; at least just the scanning portion. One common problem with any amplified device like a multicoupler is AGC or front-end overload. In simple terms, the multicoupler adjusts to the strongest signal. What you end up with is a lot of signals weaker than directly from the antenna because one signal is so much stronger than the others. These strong signals are usually FM (or TV) broadcast transmitters, cell towers or paging transmitters.

What I did was add a filter between my antenna and first multicoupler that removes all signals below 25 MHz (this includes stuff I won't be listening to anyway and AM broadcast) and the FM broadcast band. The strongest signal directly from my antenna is an FM station. After the filter the next strongest is a paging transmitter. Because the paging transmitter is in the VHF band I scan, there's no simple solution to reduce it. But the multicoupler works now because of the filter.

 

[timkilbride]

I don't have anything for strong transmitters around me. I definitely noticed a decrease in performance in my radios using it.

Tim K.

 

[kb0nly]

That Stridesburg is an overpriced piece of junk in my opinion, i tried one also, brand new, sucked. I dumped it on ebay and bought a cheap PCT drop amp, two port in my case but you can get them with 2,4,8 and i even saw a 12 port unit on ebay as well. I know a bunch of guys using these, don't overload the scanner or cause any problems for me. Its being used to split a single antenna between two scanners, the Uniden's that are my RR Feeds.

 

[majoco]

Is there a difference in reception with or without the power supply connected? Any increase in noise? Seems strange they would supply a Uniden power supply, or is that something you had to find? Correct polarity? I made up a couple of passive multicouplers (splitters?) from ordinary TV splitter/combiners and never noticed the 3dB loss.

Cheers - Martin ZL2MC

 

[kb2vxa]

"The power supply that it came with is from some sort of Uniden scanner."
This raised the following question:
"Correct polarity?"
Now I have one of my own, can the PS supply the 100mA minimum required?
No problem with the voltage and the device will only draw the current it needs so if the PS can supply more it has some headroom. Not knowing the output current I can't say whether or not the PS falls flat under load, we need these questions answered before we may properly advise you.

For information on the multicoupler follow this link:
MCA204A

 

[Skypilot007]

As mentioned above toggle the power to the multicouple while you are receiving a signal to see if you can notice any difference. You should obviuosly notice an improvement with the power applied. Test on several channels to confirm. If not it's probably toasted. You didn't acidently key up the CDM1250 did you? I use the same radio connected to a strideburge on UHF with excellent results.

 

[timkilbride]

As mentioned above toggle the power to the multicouple while you are receiving a signal to see if you can notice any difference. You should obviuosly notice an improvement with the power applied. Test on several channels to confirm. If not it's probably toasted. You didn't acidently key up the CDM1250 did you? I use the same radio connected to a strideburge on UHF with excellent results.

The PS was 750mA. I tried it both powered and un-powered. No mic on the CDM1250. The guy is offering a refund so I already sent it back.

Tim K.

 

[kb2vxa]

I caught a few giggles when I read the latest replies, I won't mention who or why because I don't want to embarrass anybody. (;->) You're better off with a new one or something comparable (remember unity gain so you won't overload the receivers) since they come with a power supply and warranty. This time keep the ohm meter or continuity tester away, both use current for measurement so if there is a DC path anywhere you're taking a chance of damaging the unit.

Good thing you can return it for refund, I guess he's not reading RR or he probably would have told you to get stuffed knowing what you did. (;->)

Thanks for the info on power supply current, that tells us it wasn't overloaded and has plenty of headroom even for my Uniden BC796D scanner. You still haven't mentioned polarity but it's a moot point now, just FYI you can fry electronics with reversed polarity. Buying anything that comes with it's own supply takes the guesswork out of it so better safe than sorry.