ICOM 7300 adj freq bleed (normal?)

[TheBlaster]

Is it normal to have S3-S7 of bleed on your frequency of choice ? Either distorted garbled deep low ...wuw wuw wuw wuw or a high thin reedy harsh bleed ?

This is what I get ALL the time when I DX (20m)..... 1/2 wave vertical, basically lossless run of coax : "Filt 1" no changes on the TWIN PBT... the RF noise floor I operate in is S0 so I don't use NR.

I am used to CB channels and this bleed is making ham radio hard work to listen to. I have only ever used a 7300 radio so have nothing to compare it to. It kind of makes sense if someone cannot hear you and then is giving a +20dB signal 2-3 kHz away from you freq that they will bleed.. but if this is normal it is a BIG downside compared to channelized SSB CB DX bands.

I have never experienced this degree of terrible bleed on CB channels... and it making ham radio a VERY unpleasant experience.

I don't know of the radio RX is poor or if it is just normal. I am guessing it is normal and you are getting either the lows or highs from the station next to you on a busy band. It is hard to make good dx in weak conditions with S3-S7 of peaking garbage on your freq.

I am very disappointed with this aspect of amateur radio, it may well be enough for me to give it up.... as I am not enjoying it. I have spent a lot of time and money on it and then I get S4-S7 of adj stations all over the freq I am on.

Yours sincerely an inexperienced new amateur radio op.

 

[sp5it]

Post a recording of that bleed.
Mike

 

[TheBlaster]

Good idea I will record when I am out next, there is some contest on this morning and I was out portable in a very low noise spot. Quite strong Euro and Russian stations... plenty of +20dB signals to have to avoid. Virtually impossible... I find a nice quiet spot ask if freq is clear and within 5 minutes I have a contest pile up on the freq (not aimed at me) or this S3-S7 adjacent bleed meaning I key up and call even more and to rid myself from having to listen to that cr@p.

I wish some these stations would ask if the frequency is clear as well, you know like a person who is not an ignorant chump... clearly that does not seem to be in their licence conditions.

If I cannot get this worked out it will be a very short lived hobby (for amateur bands at least).

 

[TheBlaster]

Here is another thing.. what is the point of a radio having a compressor to increase the average audio level and subsequent punch of the SSB RF output if the ALC is CONSTANTLY working against said increased average signal level ? Yeah... yeah keep it linear whatever.

The ALC on this radio is OUT OF CONTROL. It is a constant battle against that peaky annoying ALC meter jumping up vs mic gain vs compression.

The manual is total nonsense .. "keep it within normal 30-50pct".. that is dream world. With any mic gain above 18pct and compressor on 5 (with no dB showing on comp meter!!) it is always jumping up way high to 80 pct. As if you are EVER going to get the amount of compression (10-20dB) it suggests in the manual without the ALC being at 100pct non stop.

Could it be to save those under specced 70 Watt finals. ? I think so.

A lot of things make no sense on this radio. Yes I am relatively new but I am not a complete idiot.

I am not at all happy with this radio it is all looks and no substance in my 6 months ownership.

 

[TheBlaster]

One more thing... why is the ALC jumping up when my RF output is 50W ?

Now forgive me if I am wrong ALC is there to back off power output to keep the PA linear.. i.e. avoid IMD, saturation and harmonics being generated. So if we assume 2 transistors biased Class B push pull linear amplifier with filters. (I can be wrong here but I assume it is for now)

So if I am set at 50W and it is a 100W radio that is 1/2 spec. Now the transistors are rated at 140W for a pair. So I run at about 35 pct of maximum transistor capability.

How quick must the PA amp in this radio go non linear that an ALC must operate when your output power is 1/2 the radios rated output ?

If anyone knows an ICOM design engineer rep who can come explain this I would be very appreciative.

 

[TheBlaster]

I was about ready to drop a little coin on one of these units.
I live real close to a power substation. I’ll wait till I read a few more reviews.

A power station is most likely to not relate to the issues I mention The Howler. Any QRM produced by a power station is likely to affect any HF radio rather similarly I would have thought if the sub stations is putting out any energy at RF. Do you hear any such sounds on SW or MW bands for example, worth a check.

 

[groundwire]

You just gotta learn to set your levels correctly. And a little compression goes along way. 3db is all you need max. Anymore will just give you diminishing results, as far as voice. Some rigs will buck the alc big time but that is how they are. Again, you gotta find that sweet spot as far as the levels go. The mic you use plays a big part in the equation as well. Google is your friend. There is months worth of reading about the subject online. Grab a beer, some popcorn and get comfortable. Do some homework

 

[TheBlaster]

Which magical microphone is fundamentally different in operation than the other microphone as to affect ALC, what's the physics behind that ? (I know we have slow dynamics vs electrets or large diaphragm 48V powered condensers) None fundamentally doing a different job.

They all put out a little audio volts which is filtered down in the radio to 3kHz.

I cannot see how any mic affects your ALC working.

I even cut a load of bass out -5 to test it, ok well 300Hz then, hardly bass end but low mids which should increase headroom a little. ALC still banging up there. Nothing you do on the radio (other reduce your mic gain or comp setting) affects it.

In fact I am not even saying my transmission is sounding bad as I get good audio reports... but the mic gain vs comp setting vs ALC meter have a very clear and distinct relationship and feel to them... and that is..."You are not in control of your own radio. "

If there is a compressor the least it should be is usable before ALC starts reducing your RF power output.

Thanks.

 

[TheBlaster]

I have barely seen 1dB compression flicker on the meter.. ALC still banging away up there. So you say crank that comp a bit more to 3dB and ALC over shoot will reduce ?

How does the physics behind that work ?

 

[groundwire]

You have completely misunderstood my post. You seem very angry and defensive. Maybe you should take a breather and look into a different radio if it is not up to your standards.

 

[fourstringburn]

Icoms can be notorious for ALC overshoot so no surprise this model is no different. At least Kenwood acknowledged the 590 had an ALC overshoot and fixed it where Icom still has not on the models that do.

As for the bleed, on a busy band is where the shortfalls of an SDR receiver can be overloaded compared to a super heterodyne especially when it comes to pulling out a weak signal within the band. The newer true hetro/SDR hybrids are supposed to remedy this shortfall with SDR type receivers. This may or may not be the cause of the bleed you are hearing though.

Take SP5IT advice and post a recording.

 

[TheBlaster]

Actually you know what I think I will do... I will work it out myself.

If the solution is use a radio other than the one you are using.. well..it says it all, that is my final point here.. life is short.

 

[Ranch55]

Actually you know what I think I will do... I will work it out myself.

If the solution is use a radio other than the one you are using.. well..it says it all, that is my final point here.. life is short.

Reading your posts makes me question if you are adjusting the ALC/MIC Gain correctly.
ALC is adjusted using the mic gain with the compression TURNED OFF ....
Adjust mic gain to attain 30~50% of ALC (the red line is 0~100% of the ALC).
Then turn the compression on and turn it up to COMP 2~4 setting. Run the radio and don't be concerned with the ALC meter reading after that point.
The IC7300 works very well with that.
Also, very few 7300's RF power output % reading corresponds to the same watts output.

 

[TheBlaster]

Thanks for the reply.....yes I followed all the manual instructions.

I have concluded the ICOM mic gain/compression path and comp meter (as described in the manual which says use 10-20dB comp) is 100pct illogical nonsense and so is the manual. Ignore it totally and do this.....

Mic 5-10 pct keep compressor on 2 and forget it then the ALC stays down... I guess you can mess with the tone if you fancy but it won't be the difference between a contact or not. The end.

 

[Wire Weasel]

No radio is bulletproof against adjacent frequency "bleedover". Hams should stay 3kz. apart on SSB. If you are on a given freq. and there is another QSO going on 2kz away .... they are going to kill you. If you are getting bothered by other signals 3kz or a bit more away .... then the other signals may be VERY strong .... or you can look at your bandpass filter settings and play with them a bit. We all struggle with operating on freqs. when a given band is open strong and there's a lot of activity. It's just part of the game. Move around and try and find a clearer place to operate.