Variable power output at different frequencies Normal

[weccwwe]

Hi All,

I have 2 older ICOMs, IC746 & IC756, non pros each. Have had them for about 10 years

I have never paid attention before, but now I am wondering if this normal or I have issues with these transceivers

I hooked both ICOMs to a new MFJ872 power meter I just purchased, both in RTTY mode with autotune turned off.

Both are exhibiting power PEP outputs at different frequencies, even within the same band.

80m-ICOM756-110watts, ICOM746-110watts
40m-ICOM756-60watts, ICOM746-40watts
20m-ICOM756-70watts, ICOM746-40watts
12M-ICOM756-100watts, ICOM746-100watts

And I am measuring power variations within same band, sometimes as much as 70watts between the top and the bottom of the same band

Is this normal?

Is this because that they from the mid-late 90s, and they just getting too old to stay stable at what these advertised at 100watts?

Does newer transceivers stay stable to what they advertise?

And why doesn't the meter needle move in SSB? unless I am basically yelling into the Mic

 

[RFI-EMI-GUY]

Are you using a dummy load? A non inductive dummy load? Test in CW mode....

 

[weccwwe]

Hi, yes, 150 watt dummy load, non conductive

I dont have CW keys, but when pressing mic, I got no needle movement

Regards

 

[weccwwe]

I just did live CQ calling antenna test with my dipole, power is a little better, but not much

 

[hill]

With SSB there is no carrier, so unless you transmit a tone or voice no output.

Radios are most likely working ok. Without using a tuner, if the SWR is high on frequency the radio cut back the power.

 

[RFI-EMI-GUY]

I just did live CQ calling antenna test with my dipole, power is a little better, but not much

You are getting fooled by using an antenna instead of non inductive dummy load, and voice in SSB mode is not a good indicator of the power the radio can produce. Use CW mode and see if it matches the specs.

 

[weccwwe]

Ok will do.

Will repost fresh numbers with my Nonconductive dummyLoad and in CW

Edit: The IC746 is putting out no power in CW, keying up with mic, I have no CWkeyers, in all bands and frequencies

 

[weccwwe]

Hi all

My IC756 is doing same thing, putting out no power in CW, keying up with mic, in all bands and frequencies

 

[alcahuete]

Is that normal? No. There is nothing normal about 40W or 60W on either of those radios.

 

[weccwwe]

Thank you, I am thinking that they are failing, do radios fail slowly?

 

[weccwwe]

Is that normal? No. There is nothing normal about 40W or 60W on either of those radios.

Thank you I am thinking that

 

[K7MEM]

Hi all

My IC756 is doing same thing, putting out no power in CW, keying up with mic, in all bands and frequencies

That is normal. The PTT switch, in the CW mode, only puts the radio in the the transmit mode. Until you close the key, there will be no output. The SSB mode is similar, in that, you will not get any power out until you speak into the microphone. If you want to see steady output power with the PTT switch, try the AM or FM mode. And, do it into a dummy load.

You didn't say, or I missed it, what kind of antenna are you using. I have a IC-735, which is a little older than your radios. It works fine into my antenna and I have no problem reaching the rated output power (100W). My antenna is a 43' ground mounted vertical with 16 - 32' radials buried in the grass. I have about 75' of RG-213 going to my shack. I use a old Dentron Jr. tuner at the radio and get very low SWR readings on 40 meters through 10 meters. On 80 and 160 meters, the SWR is a little high, but usable.

 

[weccwwe]

That is normal. The PTT switch, in the CW mode, only puts the radio in the the transmit mode. Until you close the key, there will be no output. The SSB mode is similar, in that, you will not get any power out until you speak into the microphone. If you want to see steady output power with the PTT switch, try the AM or FM mode. And, do it into a dummy load.

You didn't say, or I missed it, what kind of antenna are you using. I have a IC-735, which is a little older than your radios. It works fine into my antenna and I have no problem reaching the rated output power (100W). My antenna is a 43' ground mounted vertical with 16 - 32' radials buried in the grass. I have about 75' of RG-213 going to my shack. I use a old Dentron Jr. tuner at the radio and get very low SWR readings on 40 meters through 10 meters. On 80 and 160 meters, the SWR is a little high, but usable.

Using an Alpha-Delta DX-CC 80/40/20/15/10, inverted v, center approx 40' above groound

 

[weccwwe]

RTTY into non conductive 150Watt Dummy load:

 

[prcguy]

I would repeat the test using FM mode just in case RTTY mode is trying to send data or something other than a CW carrier. Otherwise it looks like you have RF power out set for maximum and the radio should do about 100w into a 50 ohm load in FM mode. I would also make sure you have full voltage during transmit like at least 12.5V and preferably 13.8V at the radio during transmit at full power.

 

[AK9R]

150 watt dummy load, non conductive

The term you are looking for is "non-inductive". An ideal dummy load presents a 100% resistive load at all frequencies. In real life, some types of dummy loads have some inductance or capacitance at some frequencies, but you want to avoid that if possible.

What dummy load are you using?

 

[weccwwe]

The term you are looking for is "non-inductive". An ideal dummy load presents a 100% resistive load at all frequencies. In real life, some types of dummy loads have some inductance or capacitance at some frequencies, but you want to avoid that if possible.

What dummy load are you using?

I am using s Bird Termaline Coaxial Resistor Model number 8166 150watt DummyLoad

 

[weccwwe]

I would repeat the test using FM mode just in case RTTY mode is trying to send data or something other than a CW carrier. Otherwise it looks like you have RF power out set for maximum and the radio should do about 100w into a 50 ohm load in FM mode. I would also make sure you have full voltage during transmit like at least 12.5V and preferably 13.8V at the radio during transmit at full power.

Hi PRCguy

I do have the 13.8V going into the radios. RF set to maximum, going into dummyload, I am getting on FM:

3.7Mhz-8Watts
7.2Mhz-9Watts
14.2Mhz-10Watts
21.2Mhz-6Watts

Ugh

 

[RFI-EMI-GUY]

Hi PRCguy

I do have the 13.8V going into the radios. RF set to maximum, going into dummyload, Mic Keying up in RTTY, I am getting on FM:

3.7Mhz-8Watts
7.2Mhz-9Watts
14.2Mhz-10Watts
21.2Mhz-6Watts

Ugh

What do you mean by "Mic Keying up in RTTY". Are you in FM mode or RTTY mode?


Some radios reduce power in digital modes such as RTTY because they will get fried from being keyed too long.

 

[RFI-EMI-GUY]

Have you looked at the power setting options???

Transmitter
Output power SSB, CW, RTTY, FM AM	(continuously adjustable) 5–100W 5–40W