Hummm I will have to look into that, I am getting 7khz out of the radio pretty easy but I usually limit it to 5khz for harmonics.
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commercial broadcaster grade audio?
- Thread starter towerdog
- Start date
Hummm I will have to look into that, I am getting 7khz out of the radio pretty easy but I usually limit it to 5khz for harmonics.
Doing a little more research, it seems like bandwidth of the 10M4D is really 6Khz, not 4. That seems about right for a typical AM radio. (Kenwood uses the same filter width for AM too, but their filters are designed for an IF of 8.83Mhz rather than 10.695Mhz. And they cost more.
)But here's the thing: with AM you transmit the same audio signal twice, once on each sideband, with the carrier in between. The filter is centered on your carrier. This means that, effectively, rather than a single 6Khz passband, you have two 3Khz passbands.
This in turn means your high end audio response rolls off a lot sooner than you think. The 10M4D specs that I found indicate that the passband width can vary by +/- 2Khz, so in reality you may get as much as 4Khz of audio depending on the circumstances. But adding a few Khz more can greatly improve 'brightness' and overall clarity.
It might be interesting to see what happens if you wire up a relay to bypass the filter when the transmitter is keyed. Or you could just temporarily jumper it out completely if you don't mind putting up with a little extra splatter in the receiver for a while.
However this brings up an important point: no matter what you do to your transmitter, a lot depends on the other guy's receiver. Most rigs will have that same 6Khz bandwidth limit in their receive path, which means no matter what you do improve your TX audio fidelity, it might not be noticed on the other end.
Of course that doesn't mean you shouldn't still do it.
-Bill
Doing a little more research, it seems like bandwidth of the 10M4D is really 6Khz, not 4. That seems about right for a typical AM radio. (Kenwood uses the same filter width for AM too, but their filters are designed for an IF of 8.83Mhz rather than 10.695Mhz. And they cost more.
But here's the thing: with AM you transmit the same audio signal twice, once on each sideband, with the carrier in between. The filter is centered on your carrier. This means that, effectively, rather than a single 6Khz passband, you have two 3Khz passbands.
This in turn means your high end audio response rolls off a lot sooner than you think. The 10M4D specs that I found indicate that the passband width can vary by +/- 2Khz, so in reality you may get as much as 4Khz of audio depending on the circumstances. But adding a few Khz more can greatly improve 'brightness' and overall clarity.
It might be interesting to see what happens if you wire up a relay to bypass the filter when the transmitter is keyed. Or you could just temporarily jumper it out completely if you don't mind putting up with a little extra splatter in the receiver for a while.
However this brings up an important point: no matter what you do to your transmitter, a lot depends on the other guy's receiver. Most rigs will have that same 6Khz bandwidth limit in their receive path, which means no matter what you do improve your TX audio fidelity, it might not be noticed on the other end.
Of course that doesn't mean you shouldn't still do it.
-Bill
Bypass the IF Filter with a relay will introduce some kind of distorsion(been there done that)you either bypass the filter with a resistor or capacitor in TX and use diode switching scheme to use the filter in RX or you will have a very wide receiver
BTW the filter in the export are not as sharp as they seems to,they are a little wider from specs,a hammy factory filter is closer to specs or use the inrad's for a sharper filter
73 de Tecnicoloco
I could very easily be on crack. I'm looking at the "DX88HL Schematic Diagram" link here:
Galaxy Radios DX88HML Service Manual
Unfortunately it doesn't highlight the signal flows. The output of the AN612 modulator (IC3) seems to have a connection to one side of FL3 (though R80 and D19), which is above and to the left of IC3. It's a unclear what's supposed to happen next though.
-Bill
Correct.The RX IF filter has nothing to do with the TX.
If it is in the RX section then it doesn't.
I think that may be the case. Ham rigs have a low level IF section where the modes and modulation and processing is generated and then converted and amplified whereas a CB has no such section as far as I know. Maybe a few do but in the vast majority of the cases they do not.
It looks like FL3 is not an IF filter. It is an SSB filter used to filter out the unwanted sideband to make single sideband from the double sideband output from the balanced modulator.
That makes it an I.F. filter as the ssb generator is using an intermediate frequency.
I know you don't buy into the tube thing.
But as a guitarist/musician for many, many years before I got into recording and live sound, tubes are easily detectable to my ear. No self-respecting blues guitarist that I have ever played and recorded with - including bassists - would ever use a solid state rig. In recording, the tube preamps have a definable 'phat' sound that only the real high-end/ultra expensive solid state preamps could attempt to emulate. Tubes have always sounded better - and they always will - IMO . . .
I can tell the difference between EL-34s and 6L6s
I noticed earlier in this thread someone had alot of Behringer sound equipment they were using. There is alot of it on the used market and new is cheap. The bad thing is if you have a problem they offer no customer service/repair. My local music tech said they use cheap unobtainable chineese electronics and even he is unable to repair thier stuff.
Not so.
Yes it is cheap compared to some real recording equipment; yet they are still quite effective. The op amps in this gear can also be upgraded to a better quality unit. Although it works fine for what it is for the purpose of radio, the upgrades are really meant for true recording operations . . .
the big problem I see w/ 'broadcast quality' is that most radios on the air are not going to be able to hear the difference.
