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Do I have a splatterbox ?

Cabover Bob

Cabover Bob

Sr. Member
Nov 17, 2020
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RCI 6300f150 - I bought second hand and wanted to have our very well known local shop look it over before hooking it up, as I have no idea what to look for and don't intend to ever roll my own. He showed me on his Bird 43 that it was producing 250+ pep. During a brief stop today, the driver that I'm working with stated that he could hear me playing radio on 27.245, I was transmitting on 27.285. We were approximately 500 feet apart and traveling <60 mph. I am now concerned that I have been operating a splatterbox, and if so, I will have to keep it turned down until I can get our OT03 to work his magic.

Constructive advice welcomed.

Todd
 

binrat said:
250 to me seems alittle high for that radio if you ask me. You can turn it down some to see if that cures the splatter.
Click to expand...
It seems very high to me also, so I keep it turned down unless I hear the airwaves open up and I'm trying to make contact.

I have always assumed that these guys with high power gear have things tuned to where they don't necessarily bleed over. Am I wrong ?
 
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Proper diagnostic equipment will show everywhere your signal is transmitting then your tech can adjust from there to clean it up.
Surprising for the power i run and with all the other locals on near by channels that i dont get more people looking for the "bleeder" like i hear with some other "loud" locals.
 
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A quick simple thing to do until OT03 logs some bench time with it would be to have a friend drive a few miles away and try backing your Mic Gain back and find the minimum setting where the radio transmit clear. I took Shadetree Mechanic’s advice, and use a CB radio across the room that’s not hooked to an antenna as a monitor radio to set my Mic Gain, then I ask for an on air opinion. I always ran an Astatic 636 or A Road Devil with the Mic Gain set a 3 o’clock. The last time I had my Texas Ranger worked on DTB suggested using a standard Superstar coffin mic. Now I get good results for clarity with the Mic Gain at noon. Granted the coffin mics are not noise canceling. Hope this suggestion is useful. I had an episode a while back, I found out I had a splatter box. I had the Top Gun modular removed. On the scope, it was showing the extra harmonics. I was kinda embarrassed when I viewed the scope. Kinda like you wake up in the morning and it hurts to pee. The first thing I thought was, “Not me.”
 
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Thanks guys for all of the suggestions. OT03 has my other similar radio now, so when it gets back this one will be going to him immediately.

With regard to mic gain, I keep it up all the way with an SRA-198, because occasionally someone will say that my audio is low, usually while dx'ing.

Todd
 
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Don't forget the possibility of some types of CB's and how broad-banded they are and simply can't handle signals overloading the front end of the receiver which would greatly affect the ability of the receiver to sort those signals out. I'm not advocating that his radio isn't producing harmonics I would be inclined to believe it most likely is. I have a Ranger radio on the bench now that is producing a good amount of harmonics and will try to get those under control but these radios were not designed with a high level of harmonic control and every oscillator stage in a radio is most likely rich in harmonics how those harmonics are brought under control in radios marketed for the world of CB is not always up to power and can easily be circumvented by stick turners trying to find a control that will give them ONE MORE WATT! The radio I'm soon to be trying to calm down is a BULLET BOB RADIO. If you know him he is very prominent in the keydown competition world I can tell you my prelim on this radio is going to be interesting as it is only producing about 50 watts RMS but over 180 peak watts, if you know anything at all you know what that means.
 
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I have no idea what that means, other than I'm happy that it's on your bench !!

BB was the stick turner on the radio in my post, thank you Denny for helping me clean up my act.

Todd
 
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While other methods may give results... it sounds to me like this radio needs a date with a Spectrum Analyzer. That is an instrument that.... properly used.... can show you what your "frequency spectrum" looks like. You can "see" the carrier.... the modulation... AND any harmonics from OVER modulation. These artifacts are what causes channel bleedover like that. While you CAN get this dialed down using a monitor radio or helpful listeners... it is observable and measurable with a spectrum analyzer.
 
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I used to run a CLEAN Icom IC-735 at 100 watts O/P into a Wilson Shooting Star and my neighbour across the road and thru the field ran a TRC-454 or a TRC-490 with jacked up modulation and a homebrew amp running about 100 watts and a three element yagi on the flatside. She couldn't hardly be on the air if I was on 11m at the same time. I completely wiped out her crappy receiver and yet I could carry on a QSO if she was only 30 KHz away. Sometimes the fault is indeed with the TX and sometimes it is with the RX on the other end.
 
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