Adjust modulation inside President JFK mainboard PA338AB ?
- rooth
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Adjust modulation inside President JFK mainboard PA338AB ?
Hello everybody !
Do you know how modulation at JFK President ( mainboard PA338AB ) can be increased?
I made the microphone change from the dynamic variant to the elecret. It is ok, but I would like to increase the modulation a bit.
Do you know how modulation at JFK President ( mainboard PA338AB ) can be increased?
I made the microphone change from the dynamic variant to the elecret. It is ok, but I would like to increase the modulation a bit.
- ch25
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
Vr12
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- cb4ever104
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
Thought you might have tried this first before going to the trouble of changing the element.
30TM060
Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
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Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.
- rooth
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
@ ch25 : I'm not VR12 on motherboard .I looked better on the motherboard and I think it's VR5 ... What do you think?
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- ch25
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
Nope, it is PWR pot. Any AM mod/AMC labelled?
Chris
Chris
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- rooth
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
Only SQ , DEV , RF.M and S.M .
I think it must be RF.M ...?
I think it must be RF.M ...?
- ch25
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
On 338 board there is no am mod adjustment. Just found a schematic.
You can try to remove Q31 to disable limiter, but you need to adjust micgain to avoid overmodulation. Try that, if it will be too strong we try to modify AMC level other way.
Chris
You can try to remove Q31 to disable limiter, but you need to adjust micgain to avoid overmodulation. Try that, if it will be too strong we try to modify AMC level other way.
Chris
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- rooth
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
OK, I'm trying. Thanks!
- 163TM847
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
DEV is for FM modulation [DEVIATION] Dont adjust it too high though or you may over deviate.
- cb4ever104
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
Weird, or what ? Something to note for the future, and yet another reason not to buy a JFK
30TM060
Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.
Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.
- rooth
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
@cb4ever104 : No problem, I like to experiment Radio is great !
- 14CS06
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
Photo Collector CB RADIO
- ch25
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
What is have to do with topic we discuss here Claude?
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- rooth
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
The limitation with Q31 I see is for AM ... For FM I am interested in canceling the limitation.
I did not find any other references on the internet related to this ....
I think in the last instance I try to increase the power from the adjustable VR5 motherboard.
Does the power increase to the left?
Do you need any further changes?
I did not find any other references on the internet related to this ....
I think in the last instance I try to increase the power from the adjustable VR5 motherboard.
Does the power increase to the left?
Do you need any further changes?
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- ch25
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Re: Adjust modulation inside President JFK mainboard PA338AB ?
Do not cancel FM limiter, you will become unreadable.
WE ARE MOTÖRHEAD, AND WE PLAY ROCK N' ROLL
You can't have too many antennas...
You can't have too many antennas...