BCD536HP frequency issues

[spacenerd]

For the past couple months I have been having a problem with certain frequencies that I must Avoid to continue scanning. These are frequencies that are popular to my area and have not caused a problem in the past.
I have one antenna split to two scanners. The BCD 536HP and a BC335N.
I have tried disconnecting the antenna from the 536 thinking it may be some local interference. It scans just fine. Then I turned off the BC335 thinking since they are side by side possible interference. That made no difference.
Several of the frequencies in the 536 and 335 are the same. They scan fine in the 335 but lockup in the 536.
I am lost for an explanation.
There is a computer within a couple feet. Interference ?
Any ideas would be appreciated.
Spacenerd.

 

[marksmith]

A computer a couple feet away will certainly cause interference on some frequencies.

Mark
WS1095/536/436/996P2/HP1e/HP2e/996XT/325P2/396XT/PRO668/PSR800/PRO652

 

[spacenerd]

Could a computer affect one scanner and not another? And is there a way to shield the scanners from the computer?

 

[Ubbe]

Interferencies often comes from computer screens and television screens. On a computer you can change the screens frequency to change the interfering frequency.

Try to change the bandplan in BCD536HP to 5KHz steps and enter the interfering frequencies manually on the scanner and tune up and down in frequency with the squelch fully open. Find the strongest signal and then do adjustments, turn off computer screen, tv, digital box, network router, all electronic devices, until you find the source. Low quality USB cables tend to emit a lot of RF signals.

Always use double shielded coax like CATV RG6 or RG174, as single shield coax doesn't attenuate enough if you have interfering sources nearby.

Most scanners are pretty good shielded and the easy way in are through the antenna itself or directly through the coax screen.

/Ubbe

 

[spacenerd]

Thanks for the info. I turned off all electronics and it made no difference, so maybe some outside source. It is just strange that only one scanner is effected.

 

[Ubbe]

What happens if you connect only the BCD536HP to the coax, without having the split in use?
Sometimes a bad connection can create interferience, so wiggle all the connectors while listening to the troubled frequencies.

/Ubbe

 

[spacenerd]

Yes I have tried that, same problem. After spending sometime I have found one frequency (155.340) that will not scan on both scanners. It seems frequencies close to that are causing the problem. I am guessing the 536 is more sensitive than the 355. If I turn the squelch all the way up on the 355 it will scan past that frequency it will not on the 536. Unfortunately that frequency is used by local squads and hospitals. Not sure why this is causing a problem now when it didn't a few months ago. Guess I will just have to deal with it.
Thanks for everyones help.
Spacenerd

 

[KR3LC]

Try changing the intermediate frequency setting in the 536. See the manual or this online version at Easier to Read BCD436/536HP Digital Scanner Manual for instructions

Extracted form the above manual:

Intermediate Frequency Exchange See also Intermediate Frequency Exchange.

Press Channel to hold on the channel.
Press Func then 7(IFX) to toggle on or off. Press Channel to resume.


If this does not help then use tone or digital squelch if the systems you are monitoring transmit such information. The objectionable interference will still be there but at least the scanner will not lock on the channel during scan.

 

[marksmith]

155.340 is a standard EMS nationwide frequency. While a lot of people that use it may use a ctcss tone, there are probably a lot of them. However, programming this frequency multiple times with different ctcss tones that you are interested in will probably work. It will only open your squelch when signal is accompanied by the ctcss tone.

Sent from my LG-V410 using Tapatalk