Magnum S9 receive problem

[Larry-b]

I just NOW purchased a used S9 and checking things out.
The local stations that normally show S meter readings of S 9 and 10 on other radios are showing S20+ on the Magnum. One local (that is always overmodulated) now shows nearly +30 and so loud I have to turn down the volume when he talks and turn it back up to hear anyone else. Stations farther away have relatively the same S unit readings as other radios. Does the radio just need a receive alignment or is there an ALC circuit for receive?
Thanks

 

[sonoma]

here is the service manual for the S9 radio you have. shows all the adjustments to align the radio if you have the proper tools to do it with. also this radio has very good receive compared to a lot of other radios. the one you said is coming in very loud is more than likely close to you and the signal is just strong on this radio.

http://www.cbtricks.com/radios/rflimited/magnum_s9/index.htm

 

[222DBFL]

Sounds likes some front end over load from someone close, I have the same issue with my icom 746 with a couple of locals running big radios that are close, I have to turn the attenuation on to get the locals down to a level that doesn't over power the receive. The magnum radios have a good receive as my magnum 257hp has a good receive, but they can easily be overloaded with a strong close by station. Best thing to do is turn the rf gain back some or turn the volume down. Just my experience with close stations.

 

[Larry-b]

Sounds likes some front end over load from someone close, I have the same issue with my icom 746 with a couple of locals running big radios that are close, I have to turn the attenuation on to get the locals down to a level that doesn't over power the receive. The magnum radios have a good receive as my magnum 257hp has a good receive, but they can easily be overloaded with a strong close by station. Best thing to do is turn the rf gain back some or turn the volume down. Just my experience with close stations.

This S9 does have good receive I was just wondering about the higher than usual S unit readings on nearby signals and did not realize it could be overloaded that much in comparison to my Galaxy 959 and other radios. Nothing I can't deal with.
Thanks

 

[Robb]

I've dealt with a S-9 that had a recieve overload issue. Talked to Sam Lewis and Chris Holland of RF Limited about it. I told them the only solution I'd found was to use a scope along with a SINAD meter to ensure that the receive alignment was not getting square-waved. That worked . . .

It happens because someone over-tunes the receiver, as best as I can gather . . .

 

[222DBFL]

Agreed Robb, they seem to really tweak the receive on the magnum radios. All 3 of my 257hp's have very sensitive receive. My icom 746 I can hit the ATT and kill it, but with the magnums, gotta turn the rf gain down. But I will say that the receive does work well for pulling in weak stations!

 

[Larry-b]

I've dealt with a S-9 that had a recieve overload issue. Talked to Sam Lewis and Chris Holland of RF Limited about it. I told them the only solution I'd found was to use a scope along with a SINAD meter to ensure that the receive alignment was not getting square-waved. That worked . . .

It happens because someone over-tunes the receiver, as best as I can gather . . .

Thanks Robb. I just turn the RF gain back and it's tolerable. Yes the receive is VERY good and I am enjoying the S9 very much.
Thanks

 

[Larry-b]

Thanks Robb. I just turn the RF gain back and it's tolerable. Yes the receive is VERY good and I am enjoying the S9 very much.
Thanks

I just now found this from cb tricks. Thought it might bea good follow-up.
Brand and Type: MAGNUM S9
Problem: FRONT END OVERLOAD FROM VERY STRONG ‘ON
FREQUENCY’ SIGNALS (BLOCKING DYNAMIC RANGE)
Date: November 2006
Customers have been complaining about certain “S“series receivers not being able to
withstand strong, close proximity “on frequency” signals.
In some cases there is also an accompanying RF feedback during transmission.
The factory installed improper diodes in a limited number of radios. These diodes are
in the AGC at D15 and D16. To identify these improper diodes the body of this part is
much smaller than those of a standard 1N4148 and the band is “yellow”.
Magnum has been advised the Serial Numbers affected are 979 392 thru 988 080.
Please visually check the parts before removing:
D-15 and D-16 Change to 1SS53 (same polarity)
R64 and R257 remain at 2.2K or for a little added RF performance can be
lowered to 1.8K and no further adjustments are required to any circuits.
There is another trick in case replacing the diodes do not solve problem
100%.
There is a wire bundle that is laid on top of the echo board. Remove both
cable ties at each end of the echo board and spread the wires over the
entire surface of the echo board. On some radios this high concentration of
RF in the bundle creates this RFI problem. Moving the wires and keeping
them separated will eliminate the RFI.

 

[Larry-b]

I just now found this from cb tricks. Thought it might bea good follow-up.
Brand and Type: MAGNUM S9
Problem: FRONT END OVERLOAD FROM VERY STRONG ‘ON
FREQUENCY’ SIGNALS (BLOCKING DYNAMIC RANGE)
Date: November 2006
Customers have been complaining about certain “S“series receivers not being able to
withstand strong, close proximity “on frequency” signals.
In some cases there is also an accompanying RF feedback during transmission.
The factory installed improper diodes in a limited number of radios. These diodes are
in the AGC at D15 and D16. To identify these improper diodes the body of this part is
much smaller than those of a standard 1N4148 and the band is “yellow”.
Magnum has been advised the Serial Numbers affected are 979 392 thru 988 080.
Please visually check the parts before removing:
D-15 and D-16 Change to 1SS53 (same polarity)
R64 and R257 remain at 2.2K or for a little added RF performance can be
lowered to 1.8K and no further adjustments are required to any circuits.
There is another trick in case replacing the diodes do not solve problem
100%.
There is a wire bundle that is laid on top of the echo board. Remove both
cable ties at each end of the echo board and spread the wires over the
entire surface of the echo board. On some radios this high concentration of
RF in the bundle creates this RFI problem. Moving the wires and keeping
them separated will eliminate the RFI.

Question. Is the jumper board between TP-7, TP-8 and TP-9 supposed to be soldered to the terminals. I was going to align the radio and found the board soldered in place, never saw one soldered before??????

 

[Oatmeal]

Not a tech here, but I no the S9 I used to have the needle never went past a 15 on it, known of the neighbors could move it any more than that....but the receive had that crystal clean sound to it..