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doesn't make sense to me

When a radio is tuned for ONE Specific frequency, all the effort goes into that one frequency...

You said you tuned to 1000hz

the radio was tune using a 1000hz tone

So any sort of audio CLOSE to that freqoency of tone, will also pass thru easier than the LOWER tones or, in reality, any range of tones above and below that "tone tune" will not pass as well.

The simple Cobra 29 is set up to pass more voice than whistle, not saying it can't be done, your radio proves this, but the tone you're trying to pass thru is not your true voice range.

upload_2021-5-27_17-37-45.png
I mean, come on!
Whistle is closer to a tone and
an over modulated one at that!​

Many people would open up the radios' band pass to make it more Hi-Fi - Wi-Fi on 11 meters,.

But the effort of using the whistle for a swing in a tune up of 1,000Hz tone is pushing the upper limits of the radios own BUILT-IN band pass...

Besides, you have a Big Huge CHOKE called a Modulator you gotta push all the colors thru...tends to kinda limit the whole effort of making it pass - when you tune for one side of the spectrum and forget there's' a whole bunch more that makes up your voice - and all for a silly little meter called a BIRD that you feel is more important to watch swing, than to pay attention to the actual conversation and saying "Hello".

The idea of the Modulator is to change your Audio voice component into a range of frequency as a power to be mixed in with 27MHz and call it AM.

The choices of Capacitor value used (say 330uF to as much as 1,000uF) and the Modulators' number of winds themselves, limit your ability to pass everything - it's "pre-set" for a range of vocal tones, not just whistle.

So you're limited right from the start, and why some people use Galaxy's AM Regulation method to pass more audio - also at a price - so it's a give and take.

Please, don't focus so much on Bird watts, they get you into trouble every time - focus more on sounding good to others, that's where the money is, or at least you should throw your $$$ it in that direction - people hearing a good sounding radio makes your voice, your thoughts, get heard, and understood, not a whistle.

.
 
this is the mod i did =Change R228 to a 1.5k ohm.
Solder a 1uF, non-polarized capacitor from pin 9 of the audio IC to the junction of R228/D63/R194.
Replace the AM pass regulator with a TIP41C.
Set your dead key to 1.5~2W

maybe the voltage at junction R228.D63/R194 is to low at that wattage?? i can't measure it at this given moment like i stated I'm recovering from rotator cuff surgery

From what you describe, your radio sounds like it has no "" swing kit "" in it.
Most radios, as you turn down the dead key, the peak will drop as well.

What is a Exit 13 tune?

And
I agree with Nomad:



And, as has already been said a bird on AVG is not the proper way to measure AM.

73
Jeff
 
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this is the mod i did =Change R228 to a 1.5k ohm.
Solder a 1uF, non-polarized capacitor from pin 9 of the audio IC to the junction of R228/D63/R194.
Replace the AM pass regulator with a TIP41C.
Set your dead key to 1.5~2W

Ya' kinda went the wrong way...

upload_2021-5-28_8-28-26.png

You need the influence of the cap to hold down the lower end of the envelope "swing" ...

As it recharges, so does the swing "rise", you need to replace the R228 back to the 560 - play with R195 instead.

Not to go into a lot of details but the 1.5K resistor mod, that value is already there.

  • note how 1K is R194 to one side, as 1.5K is R195 - to the other...

The location of the 560 and the 1K affect how that diode flows power out of, and into - that cap - that is where the lower limits are set. You can only get so much power out of this design - then you'll have to settle for what you've got.

A better way is to mess with the 1.5K on R195 and that side of the circuit - you can try various methods to help here - including what is done at JP36 on a 29'. I'll leave it at that...
 
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thanks, andy back to the drawing board it is

Ya' kinda went the wrong way...


You need the influence of the cap to hold down the lower end of the envelope "swing" ...

As it recharges, so does the swing "rise", you need to replace the R228 back to the 560 - play with R195 instead.

Not to go into a lot of details but the 1.5K resistor mod, that value is already there.

  • note how 1K is R194 to one side, as 1.5K is R195 - to the other...

The location of the 560 and the 1K affect how that diode flows power out of, and into - that cap - that is where the lower limits are set. You can only get so much power out of this design - then you'll have to settle for what you've got.

A better way is to mess with the 1.5K on R195 and that side of the circuit - you can try various methods to help here - including what is done at JP36 on a 29'. I'll leave it at that...
 
"When a radio is tuned for ONE Specific frequency, all the effort goes into that one frequency...

You said you tuned to 1000hz"

1iwilly said: ↑
the radio was tune using a 1000hz tone

"So any sort of audio CLOSE to that freqoency of tone, will also pass thru easier than the LOWER tones or, in reality, any range of tones above and below that "tone tune" will not pass as well."

blah blah blah.

step #10 of the 148gtl transmitter alignment procedure.
148gtl, gtl/st and gtl nw/st, revision 1.111, 03/11/03 Burke

tx mode, channel 19 am mode dynamike maximum.

modulation meter to antenna input. insert 1KHZ., 50mV. signal to microphone input.

adjust VR501 AMC control for 90% modulation.


(adjust vr10 in am mode for 5.60vdc at the emitter of tr41)
switching out the 2SC1419 for a TIP41 is a waste of time.
 
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"When a radio is tuned for ONE Specific frequency, all the effort goes into that one frequency...

You said you tuned to 1000hz"

1iwilly said: ↑
the radio was tune using a 1000hz tone

"So any sort of audio CLOSE to that freqoency of tone, will also pass thru easier than the LOWER tones or, in reality, any range of tones above and below that "tone tune" will not pass as well."

blah blah blah.

step #10 of the 148gtl transmitter alignment procedure.

tx mode, channel 19 am mode dynamike maximum.

modulation meter to antenna input. insert 1KHZ., 50mV. signal to microphone input.

adjust VR501 AMC control for 90% modulation.
That statement had me confused. Tuning in the center of the speech bandwidth, is exactly what you're supposed to do.
 
ok i put the 560-ohm resister back made no different took the mod out and put the RS transformer with 2200uf cap now the radio takes off look at video=https://www.dropbox.com/s/ynx6rkdu6j5aezk/20210528_115543.mp4?dl=0
2200 mfd is a lot in this location. I recommend about a thousand mfd. With the cap as large as it is now, you are passing a lot of low frequency response that can cause the modulator chip to draw excessive current. Some chassis will cause the eight volt regulator to drop out of regulation and mess the PLL circuit up. When this happens the symptom is very garbled AM audio. I've noticed the newer the radio is, the more sensitive it can be to this problem.
 
i knew there was an update just could find the info 1000uf it is thanks shockwave i'm happy with the results i never got the same watts out of it when i tried the 29 transformers best was max 7 1/2 watts compare to this transformer almost 11 watts



2200 mfd is a lot in this location. I recommend about a thousand mfd. With the cap as large as it is now, you are passing a lot of low frequency response that can cause the modulator chip to draw excessive current. Some chassis will cause the eight volt regulator to drop out of regulation and mess the PLL circuit up. When this happens the symptom is very garbled AM audio. I've noticed the newer the radio is, the more sensitive it can be to this problem.
 
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am receiver selectivity (passband) for the 148gtl is 3 KHz (-6 dB), 9 KHz (-50 dB)

You're forgetting ...

The technology used in todays Mic's are a lot different, why do you think more people tend to use the older microphones with the older sets?

You go ahead and keep quoting regulations, the rest of us are still going to work with the customer - not matter what YOU may say...
 
I've always used the old school coffin mikes 2nd choice superstar mike


You're forgetting ...

The technology used in todays Mic's are a lot different, why do you think more people tend to use the older microphones with the older sets?

You go ahead and keep quoting regulations, the rest of us are still going to work with the customer - not matter what YOU may say...
 
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