bcd 346 xt versus bcd 125at for airband

[stormtracker78]

hi out there airband fans i need some experienced scanner info in relation to the airband recently i have set up a base station for sw and ham and scanner based listing i have a bcd 996p2 whistler 1065 bcd 396xt and 346 xt and also djx11 alinco i bought a stridsberg multicoupler to combine them but when i plug it in the preamp will make distortion on the airband signal sometimes also on the railband so im using it unplugged since im doing that i need the best reception possible ive noticed out of all my scanners the 346xt and alinco has the best and most sensitive reception but i heard that the bcd125at is the best for airband but it doesn't trunk is the 346 the same sensitivity really the same internal design but with trunking ability i really would like to get the best reception possible if there the same i can save money but if there is a big considerable difference i would love to know i have a tram antenna mounted 20 feet high with lmr 400 abr coax any suggestion or info MUCH appreciated

 

[Ubbe]

i bought a stridsberg multicoupler to combine them but when i plug it in the preamp will make distortion on the airband signal sometimes also on the railband

It's a shame that it doesn't have better quality for the money you pay. I experiance the same that it overloads easily even at moderat levels and it is not suitable for low signal level scanning due to it's bad preamp specification. Try using a FM broadcast filter in front of it and as it takes the whole 25-1000Mhz range you could need some other filters depending of if you also have a TV transmitter nearby or perhaps a cellular tower that could saturate the preamp and loose sensitivity.

AM reception works by detecting the signal level at the demodulator detector and reduce the gain in the different amplifier stages in the receiver to not have the signal top out and hit the roof that would clip an AM signal and distort it. Sometimes that regulation in some receiver designs results in the gain being too low with bad sensitivity and low audio. The BCD125AT seems to have that gain level set to an optimum value. I actually modified my UBC780XLT to give a higher gain in AM and that improved both low signal performance and audio levels, although VHF air where already pretty good from the front end filters using tuned varicap filters that follows the frequency in the VHF band.

I believe most AM mode in scanners could be improved if the gain levels operation could be set by the user to give best possible reception. All HAM gears for AM/SSB have user adjustable gain, or an automatic gain function that seems to be much more dialed in than what they are in scanners.

/Ubbe

 

[stormtracker78]

Ubbe!! Ty once again! Yes I agree I talked to stridsberg before I ordered to decide between the passive or the preamp they told me to get the preamp as supposedly if it's not plugged in it's the same as the passive so best to go with the preamp I would have the best of both worlds the airport is actually in my city but yes I get bad overload and also some overload from the railyard which is only 5 miles away as well the locomotives come in real loud and clear it's the handhelds that dont and you hit it dead-on on the frequencies on the 800 it works fine the but low VHF and below not so well would you recommend this as the FM broadcast filter or another model possibly you might have used? HPN-30118 Combined Notch Filter | Scanner Master

 

[spacellamaman]

sorry i didn't read the post carefully enough.....

 

[stormtracker78]

Ty guys for the info does any one know of a good fm broadcast filter, scanner master is out so thinking getting the sdr dongle or flamenco

 

[popnokick]

All meaning lost to me... periods at end of sentences would help. Stopped reading when I couldn't figure out whole questions / thoughts / related vs unrelated thoughts. Sorry.

 

[stormtracker78]

Lol sorry I have a sprained wrist atm (atm means at the moment to help you understand ) hurts some to type perfectly.

 

[popnokick]

Hope you're healing quickly! There are several FM trap filters on Amazon (including the ones you noted). This one "out specs" those and is highly regarded elsewhere on RR - VHF-FM Broadcast Filters | PAR Electronics | Filters for the commercial 2 way market, MATV, FM broadcast, laboratory, marine industry, amateur radio, scanner and short wave listening enthusiasts

 

[Ubbe]

You can check out some common filters at this link: FM bandstop filter comparison | RadioReference.com Forums

/Ubbe

 

[stormtracker78]

Ty very much Ubbe and popnokick. I ordered the rtl sdr 88-108 fm broadcast reject filter the other day, should be coming in today as a matter of fact. I want to see if that does indeed fix the problem somewhat, if it does I plan on getting me the par filter because it's also the VHF rail band that is suffering as well. So I figure I'll try it with a cheap filter before I invest money in a better one to see if that is the case which I do think it is. Thank you all so much for giving me the place to go to get really good quality FM filters. 👍

 

[stormtracker78]

Well I've had several days to tinker around with it and these are the results. It does not help the stridesburg, in fact it increases the amplified noise threshold however it's a clear noise threshold compared to when I wasn't using the dongle. Now the kicker is when the stridesburg is unplugged it does fantastic in the 130 to 138 range between 108 and 125 somewhat of an improvement I did find two new frequencies so I do think the filters are warranted but will they work with my stridesburg? I'm still going to be testing I'm thinking the par and others might be a better selection (I have the sdr hooked in between the one 400 coax and the stridesburg. I also tried it from the Stroudsburg out to one of the scanners still same problem of noise)