Brendan1
15-10-2007, 01:44
I have found an assembly error in my RX320D only today, after some 4 years of ownership.
NOTE: RX320D owners may wish to check the internal circuits of their radio!
Here's my story: While in the early stages of installing an attenuator pot in the 12 kHz IF audio output today, I found that the sides of the IF audio line were shorting out due to sloppy assembly work. At the jack assembly, there are two 1200 ohm resisters and a 100 pf capacitor installed to attenuate the hot IF audio. These components are not documented in the TenTec schematics online for this radio.
From the jack assembly there are two leads, one coming from the IF board, and another going to the DSP board. The attenuation circuitry is installed at the jack, between the two leads, and as built in my radio, can short across the positive and negative sides. The two sides (center conductor and shield) were so close I thought they were actually soldered together.
Upon close examination they were not soldered but touching nevertheless. I separated the two leads, installed some insulating tape, and fired up the radio.
My audio is now so good, my SNR has gone up by at least 3dB during some preliminary testing, and I will continue testing to confirm total gain.
My DRM logs have suffered from low SNR values (a maximum of 22dB) since I began serious logging and listening about two years ago. Several correspondents remarked on this, and felt my equipment was capable of higher SNR figures. I found that RX320D's are supposed to run "hot" IF audio out and I should not have the issue of low SNR figures. My SNR has been low, but not by so much as to make reception impossible, only more challenging.
My logs should be quite a bit better from now on, and I may still need to install the 10K pot to turn down the volume, as was my original intent.
To sum it up: owners should check the 12kHz IF output jack to ensure that the lead assembly is free from shorts. A gentle tug, a piece of tape, and mine was fixed. I never had occasion before today to even look at the jack and wiring, so I must admit to feeling a little foolish as to finding this fault only today, nearly four years after purchasing the radio.
I'd appreciate hearing from anyone who may also have had or has this problem now.
NOTE: RX320D owners may wish to check the internal circuits of their radio!
Here's my story: While in the early stages of installing an attenuator pot in the 12 kHz IF audio output today, I found that the sides of the IF audio line were shorting out due to sloppy assembly work. At the jack assembly, there are two 1200 ohm resisters and a 100 pf capacitor installed to attenuate the hot IF audio. These components are not documented in the TenTec schematics online for this radio.
From the jack assembly there are two leads, one coming from the IF board, and another going to the DSP board. The attenuation circuitry is installed at the jack, between the two leads, and as built in my radio, can short across the positive and negative sides. The two sides (center conductor and shield) were so close I thought they were actually soldered together.
Upon close examination they were not soldered but touching nevertheless. I separated the two leads, installed some insulating tape, and fired up the radio.
My audio is now so good, my SNR has gone up by at least 3dB during some preliminary testing, and I will continue testing to confirm total gain.
My DRM logs have suffered from low SNR values (a maximum of 22dB) since I began serious logging and listening about two years ago. Several correspondents remarked on this, and felt my equipment was capable of higher SNR figures. I found that RX320D's are supposed to run "hot" IF audio out and I should not have the issue of low SNR figures. My SNR has been low, but not by so much as to make reception impossible, only more challenging.
My logs should be quite a bit better from now on, and I may still need to install the 10K pot to turn down the volume, as was my original intent.
To sum it up: owners should check the 12kHz IF output jack to ensure that the lead assembly is free from shorts. A gentle tug, a piece of tape, and mine was fixed. I never had occasion before today to even look at the jack and wiring, so I must admit to feeling a little foolish as to finding this fault only today, nearly four years after purchasing the radio.
I'd appreciate hearing from anyone who may also have had or has this problem now.