Magnum 257HP ,Poor TX audio , tried several mics ,SSB ALC , Bias no effect . Did not align TX lower stages . AM , FM are perfect , all RF power outputs perfect , looks good on scope with generator but cant send 2-tone for ssb , mic sens is high but distorted , coukd it be that special compressor ? Problem is less noticable if i crank up the mod and sound like an idiot AM'er calling 'Skipland' but I dont want to sound like that , I use it for Ham .

Dbl check your swr in am mode.. Ch your ssb power and mic gain default is 50 on both on hf .. If you use the mh-59 you will need to reduce the mic gain to 35 and it needs to be set for remote mic in the menu. Also the ssb needs to be set 2.5k wide with the ssb carrier zeroed both tx and rx

You may have a radio where the AM limiter has been defeated which can cause all kinds of issues. I would first check the mic is wired right and does not have a problem, the radio should have output with a tone to it on sideband--wattage up to over 20 watts on SSB is normal.

on ssyou are some what familiar with working on radio's. just make sure before you pull your hair out aligning the radio that you made sure it definitely is not tx on ssb. b the.Mic gain will increase the modulation. it could just be a meter issue. confirm this by having some one on another radio on ssb the same channel listen for you. if he cannot hear you then the ssb is blown out.sounds likelike

In answer to your question, no, it is no a problem with the final. I would try turning the ALC control (VR12) until you have 45 Watts out. (Ref Magnum S9 alignment procedure on CBtricks.com.

....Don at NTCB, Inc.

Adj VR1 next to VR2 they are in the center of the main motherboard. VR1 will allow you to adj the S meter in AM mode only.

Nope, your not the only one. Poor power regulation internally and maybe check your antenna swr. Higher wattage with even 1.9:1 i have seen exports have issues.. and then the magnum with there alc mod (compressor) on the op amp..

hELLO THERE
hERE IS SOME MODIFICATIONS FOR THIS RADIO
Galaxy Mods DX 2527 - VR 1....AM/FM S-Meter, VR 2....SSB S-Meter, VR 3....SSB Squelch Range, VR 4....AM/FM Squelch Range, VR 7....SSB Carrier Balance, VR 8....RF Meter, VR11...Driver Bias, VR12...SSB ALC, VR13...Hi Power, VR14...AMC, VR15...AM Low Power, VR16...SSB Low Power, VC 1....10.240, VC 2....10.240. DX 2517- VR 1....AM/FM S-Meter, VR 2....SSB S-Meter, VR 3....SSB Squelch Range, VR 4....AM/FM Squelch Range, VR 5....FM Deviation, VR 6....SSB Carrier Balance, VR 7....TX Offset, VR 8....CW Beep Level, VR 9....RF Meter, VR10...Final Bias, VR11...Final Bias, VR12...Driver Bias, VR13...SSB ALC, VR14...AM/FM High Power, VR15...AM Modulation Meter, VR16...AM Modulation, VR17...SSB Power, VR18...AM/FM Low Power, VR601..13.8 Volt Power Supply. DX 22B- VR 1....AM/FM S-Meter, VR 2....SSB S-Meter, VR 3....SSB Squelch Range, VR 4....AM/FM Squelch Range, VR 7....SSB Carrier Balance, VR 8....RF Meter, VR11...Driver Bias, VR12...SSB ALC, VR13...High Power, VR14...AMC, VR15...AM Low Power, VR16...SSB Low Power, VR21...TX Offset, VC 1....10.240, VC 2....10.240. DX 11B- VR 1....AM/FM S-Meter, VR 2....SSB/CW S-Meter, VR 3....SSB Squelch Range, VR 4....AM/FM Squelch Range, VR 5.....FM Deviation, VR 7....SSB Carrier Balance, VR 8....RF Meter, VR10...Final Bias, VR11...Driver Bias, VR12...SSB ALC, VR13...AM/FM High Power, VR14...AM Modulation, VR16...CW Tone Level, VR20...Final Bias, VR21...TX Offset, VR601..13.8 Volt Power Supply, VR803..AM/FM Low Power. DX 77HML, DX 88HL, and DX 99V- VR 1....AM/FM S-Meter, VR 2....SSB S-Meter, VR 3....SSB Squelch Range, VR 4....AM/FM Squelch Range, VR 5.....FM Deviation, VR 7....SSB Carrier Balance, VR 8....RF Meter, VR10...Final Bias, VR11...Driver Bias, VR12...SSB ALC, VR13...AM/FM High Power, VR14...AM Modulation, VR16...AM/FM Low Power, VR20...Final Bias, VR21...TX Offset.
Unmarked VR in R189..AM/FM Medium Power for DX 77HML only. DX 33HML, DX 44V, DX 55V, DX 66V, and DX 73V- VR 1....AM/FM S-Meter, VR 4....AM/FM Squelch Range, VR 5.....FM Deviation, VR 8....RF Meter, VR12...Low Power AM Modulation, VR13...AM/FM High Power, VR14...High Power AM Modulation, VR16...AM/FM Low Power.
Unmarked VR in R188..AM/FM Medium Power (DX 33HML only)
Unmarked VR in C139..Med Power AM modulation (DX 33HML only) DX 949,DX 959- VR 1....AM S-Meter, VR 2....SSB S-Meter, VR 3....SSB Squelch Range, VR 4....AM Squelch Range, VR 6.....SSB Carrier Balance, VR 7....TX Offset, VR 9....RF Meter, VR10...Final Bias, VR12...Driver Bias, VR13...SSB ALC, VR14...AM High Power, VR15...AM Modulation Meter, VR16...AM Modulation, VR17...SSB Power, VR18...AM Low Power, VC1....10.240. DX 2517 and DX 2527-
Symptom:Buzzing or motorboating sound in either the transmit or receive.
Problem: TR602 is oscillating
Cure: Replace C602 with a .01uF cap {Cap is located in the power supply board}.
RG 66,99,DX2517 Replace Q54 2SB754 60watt 7A with a higher power 2SB817 100 Watt 12A. Derating of this component will cool operation, provide better voltage stability,decrease wobble, allow voltage increase to 14.5 volts comfortably. (replace 10 volt caps in this section of the radio to a minimum of 16 volts before increasing supply voltage to this level)and provide faster swing rise time, Replace Q37 2SA473 to a 2SA1012-0 or ECG153 this will improve the clarity and volume of the modulation and it will also run a lot cooler.

You've replaced the pre driver, the drivers and finals. Set bias and still low output. The pre driver is the same transistor used as the tx exciter transistor on other pcb chassis on bottom of radio. Follow the gray coaxial wire from the pre driver on the RF circuit board back to the tx/rx i.f. Circuit board. The gray coax cable plugs right next to the tx exciter transistor on this pcb. Again it's on a different pcb all together and on the bottom of the radio and also. Replace it! And check for open bias or emitter to ground chip resistor next to it. You will get your drive back. Very few rigs have I seen the actual Finals blown in the mosfet or the bipolar version. Just the driver stage with a week pre driver and the SMT "pre" pre driver on the same RF pcb. And the tx exciter on the other pcb.

Hello.I have a similar situation on a Magnum 257 HP operating on SSB (AM and FM works fine). If i Transmit it works fine, but when i release the Mic button (after TX), in the bottom side were the RX level should be, it appear somth like a signal level 3 to 5 (constant and continous), but i can't get any reception at all. Only if i turn the TX power level to MAXand i transmit, then it goes back to reception, but not every time. Somtime after TX i need to push the mic button 2-3 times to make it recive somthing, but this wors only if the power level is over 60-70% an i repeat, only on SSB.Can i get some help with this issue?

tintlady, here is the info you requested;
the AM limiter is R 276

These are the variable adjustments inside,and what they control.
VR-1 AM S-METER
VR-2 SSB S-METER
VR-3 SSB SQUELCH RANGE
VR-4 AM SQUELCH RANGE
VR-6 SSB CARRIER BALANCE
VR-7 TX OFFSET
VR-9 RF METER
VR-10 FINAL BIAS
VR-12 DRIVER BIAS
VR-13 SSB ALC
VR-14 AM HIGH POWER
VR-15 AM MODULATION METER
VR-16 AM MODULATION
VR-17 SSB POWER
VR-18 AM LOW POWER
VC1-10.240 MHz Frequency adjustment

Hope this helps you out, let me know,,Mechanic