qrm eliminator ptt lead.

Hello all.I am looking at trying a qrm eliminator on my 11 metre kit. Does anyone have experience of using the crt9900 with the qrm eliminator with respect to the ptt cable. Some radios have a  built in socket but not the crt 9900. Thanks

Hi Andrew,

Unfortunately there's no real simple way to connect up your 9900 to a typical QRM eliminator unit.

There have been many ingenious 'modifications', some by adding RF sensing switch circuitry to the QRM eliminator and others by adding a PTT output to the CB in question. (The latter requiring a good technician to perform.)

There were some QRM eliminators offered that had RF sense switching built right in but after a quick scoot around I couldn't find a readily available off the shelf commercial unit offering such.

Also you can find RF sense switch boxes but some won't be suitable for your needs and as ever always commercially expensive for what they are.

Although I have a typical QRM eliminator unit that I use successfully (my Ham radios having PTT output lines) and wrote about my adventures with such a unit recently there are other options to try out first. I mentioned in that article that it was always worth trying RF attenuation principles first and in your case that would be performed via the RF Gain control. You'd be surprised that as counter-intuitive as it seems by turning down the RF Gain you can actually start to hear signals buried slightly in the noise and become far more readable.

As ever station setup is the most important thing to consider when it comes to 'noise' by utilising good quality coax with careful routing as well as good connectors throughout. When using a mobile mounted radio you can get away from man made noise found at home especially in built up areas. Nothing better than sat atop a hill away from the maddening crowd for quieter reception as well as antenna height gained by such an excursion.

For a home setup there's the often quoted advice of running your CB from a battery and then to turn off the house electrics via the main breaker/switch box to see if your noise is reduced. This helps you discover if your very own property is the source of any RFI or electrical noise. (You'd be surprised of how often it is.) Usually but not always this is the mainstay of the Ham operator who suffer dreadful noise problems down on the lower frequencies the upper frequencies not being so badly affected in comparison. (Depending on the culprit/cause of the noise source....a phone charger of my wife's got thrown in the bin after discovering it spewed RF signals on the upper bands!)

You'll also have to remember that although we can get good 'skip' conditions helping our CB fun it also tends to bring an increase in noise as to be expected. There isn't a lot you can do about this even with a QRM eliminator.


Apologies for the rather long winded response (me? ) but I do like to be thorough knowing that more than one person will be reading this posting now and possibly in the future.

Long story short, try turning down the RF Gain control....you'd be surprised at how well that can work.  


I wish you well with your radio operations there Andrew.

All the best,
Victor

Many thanks. I was afraid that a quick fix was not going to be easy. Thanks for your review and reply.

buy a new radio from knights new Anytone, Ares it works but there is strange thing you listen its like a mobile phone, it sounds it works but were it goes to
strange knock of qrm and you get low down chats it works to but i would love try what freqs it is when switched on