Other filters such as LF-H8S work ok too, try to find a filter with similar impedance and insertion loss, the wide boys sound much better with a wider filter,Ī switched if bandwidth board would be a cool mod, a socket to plug n play filters would be better than nothing, You can improve the fidelity to hear what the wide boys are transmitting if you are willing to sacrifice selectivity by changing the 455ht to something like a Imagine the resistors and capacitors acting together as a frequency variable divider network.
#Essb audio samples series#
Part of the bandwidth is set by the 455khz second IF filter as stated above often a cfw455ht 6kc and partly by the caps/resistors in the audio chain after the detector,Ĭaps to ground reduce treble, higher value less treble,Ĭaps in series effect bass, higher value more bass, You have two methods to widen your receiver, first IF in most cb's is a 300kc or so ceramic filter unless its a modern rig with 7 or 8kc first IF crystal filter,
#Essb audio samples software#
With rigs like the Flex, the filtering is entirely controlled by software and can be as narrow or wide as you want it, without having to use crystal filters. Personally I keep hoping the SDR radio craze comes to 11 meters some day. (Not all of us are able to run a gazillion watts like the guys on the superbowl, so we need to find other ways to make ourselves stand out. Some people consider it a worthwhile area of experimentation. So is it worth it to go to all the trouble to make your station sound that good on 11 meters when most people won't be able to appreciate it? I guess it depends on your perspective. And the missing highs really do make a difference when listening to a wide AM signal. So yeah, tweaking the AF stages in a given rig will allow you to recover a lot of lost low end, and will gain you a little bit at the high end, but you'll still be limited at the RF level by the crystal filters. Bypassing the filters yields the best results, but the 12Khz setting is pretty good too. (There are a few caps you can change to widen the AF response out a little more, but I think it's pretty good as it is.) When the receiver is set so that the 6Khz filters are engaged, you can still hear the bassiness in the audio, but cutting out the highs makes it sound more muffled. The audio circuitry of the receiver has not been modified. Most of the tests are done with the 8.83Mhz and 455Khz IF filters bypassed. One more test with all the filters in the receiver bypassed again Ditto, with the receiver set to use the 12Khz filter (at the 455Khz IF) Ditto, with the receiver set to use the 6Khz filters Ditto, with the transmitter restricted to 3.1Khz of response Behringer B1mic and audio gear through the rear panel ACC2 port MC-60A desk mic through the front panel MC-43S hand mic through the front panel (Yeah, I know this is ham gear instead of CB gear, but the idea still applies.) The samples are: I had some time to putz around a bit this weekend, so I made a sample recording of my rig, illustrating what it sounds like when you try to cram HiFi audio through a 6Khz crystal filter. HiFi audio sounds much crisper with the increased bandwidth. There is a noticeable difference on AM between 6Khz and 12Khz or bypass. There are options for 2.7Khz, 6Khz, 12Khz and 'bypass,' where filtering is disabled entirely. The Kenwood TS-850SAT that I have allows you to select the filter width at both IF stages from the front panel. Hopefully I'm not wrong about the filters being a limiting factor for RX response though. (Note that earlier I had asserted that these filters might limit TX response too, but that was a mistake on my part. With the MMM mod, you should be able to hear all the low end, but if you listen to someone with a really wide signal, they may have highs up around 5 to 6Khz which will be lost. Having a 6Khz AM filter bandwidth actually results in about 3Khz of actual audio bandwidth, since AM has two sidebands. I think you're still limited a bit by the crystal filters though.
#Essb audio samples mod#
I actually found a recording on youtube that seems to show the difference:ĬB RADIO COBRA 148 GTL AFTER AND BEFORE THE SRC WIDE RECEIVE MOD - YouTube It looks like this mod mainly improves the response of the AF circuits.