KSB2 off frequency?
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I continue to struggle to get my KSB2 to sound as good as other rigs. I've
heard other K2s on the air and know it's my individual problem. I was testing today on 7265 LSB trying out two different mikes - Elecraft MD2 and Ten Tec 706. The station listening said: - the Ten Tec has no lows and lower output - the MD2 sounds too bassy and muffled - the MD2 sounds fine if he tunes up 40 hz from my frequency Based on this, I recorded both from the audio on a separate receiver. I agreed, the MD2 sounded bad on frequency, but sounded normal if I tuned up about 40 hz. The Ten Tec had no lows and changing frequency made little difference. But, it took more voice to trip the VOX with the Ten Tec. Would this be due to my filter setup? Will adjusting the OP1 filter bring my transmit frequency back? Do I need to move the filter up or down? Will changing KSB2 R14 from 1k to 2-3K help the Ten Tec mike drive the KSB2? All help greatly appreciated. 73 de NA8M John _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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John, NA8M wrote:
...the MD2 sounded bad on frequency, but sounded normal if I tuned up about 40 hz. The Ten Tec had no lows and changing frequency made little difference. But, it took more voice to trip the VOX with the Ten Tec. Would this be due to my filter setup? Will adjusting the OP1 filter bring my transmit frequency back? Do I need to move the filter up or down? Will changing KSB2 R14 from 1k to 2-3K help the Ten Tec mike drive the KSB2? All help greatly appreciated. --------------------------------------- Regarding audio quality: 1) Are you properly tuned into your own signal when monitoring? Depending upon how you've calibrated your K2, your frequency reading may not be the exact frequency, so it's normal to tune for best sound. Also, is XIT turned off? If your rig is more than 10 or 20 Hz off frequency, you can improve the dial accuracy by properly calibrating the master clock on the Control Board. See the instructions for calibrating C22 on the Elecraft site under Builder's resources. Even when calibrated, a dial error of up to about 30 Hz is common, because of the resolution of the logic circuits used. 2) What filter bandwidth are using for OPT1? It is fixed, but can be changed by changing components on the SSB board. The basic K2 SSB module has a filter bandwidth of just about 2 kHz. That's 'tight' for most SSB operators. It can sound good and, most importantly, has the greatest "punch" when set up just right (tighter bandwidth concentrates the RF in a smaller slice of spectrum). But its adjustment is very touchy. Many SSB operators prefer to use the mod kit available from Elecraft to widen the SSB filter out more like other rigs for better overall sound and ease of adjustment. 3) How did you set up your BFO frequencies (CAL FIL)? It has been my experience that using Spectrogram is simply not good enough to know that the setting is optimal. As the SSB manual says, it takes listening to your own signal to make the final "tweaks" of the BFO settings in most cases. This is especially true when using the 'stock' narrower filter. A little experimenting while listening to your own signal will quickly show you which direction to move the BFO frequencies. 4) How old is your SSB module? Some of the very early modules had crystals that were even tighter than the current crop. Some produced bandwidths well under 2kHz and it was simply impossible to set up the SSB board for good audio. That issue was addressed several years ago, but if you have an early board that you are only now putting to work on SSB, that might be the case. Spectrogram will show you the overall filter bandwidth. Regarding drive level: Are you seeing ALC action on all bands? Press and hold DISPLAY RF/ALC to switch between RF output and ALC action. The bar graph reads backwards (right-to-left) in ALC mode. If even one bar of ALC is flickering, you have plenty of drive from the mic - enough that the K2 is automatically reducing the gain to prevent over-driving. If not, then raising the value of R14 can help. There are other possible mods to increase the drive shown on the Elecraft web site. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by John Huffman-2
John,
I must ask - how did the receiving station know he was actually tuned to your frequency if he did not tune for the best sounding voice. If both of you were relying on the indicated frequency of the tranceiver, there are two places for error to creep in - his transceiver calibration and your K2 dial calibration - either are suspect - amateur transceivers are not precision frequency counters and you said the error was only 40 Hz. Be aware that 20 Hz accuracy is about the best that you can expect from the K2 and many other transceivers even when they are properly calibrated. Before you do anything, I suggest that you check the dial calibration on your K2 against WWV. 40 Hz is not a lot - if it were 400 Hz, that might be something to be concerned about, but 40 Hz is almost 'on frequency'. You will likely have to tune WWV with precision, and the only way I know to get closer than 30 Hz is to use Spectrogram to observe the 500 and 600 Hz tones. Perhaps some folks with perfect pitch can get closer than 30 Hz, but I certainly can't without a pitch measurement tool. If you find your Dial Calibration OK, then yes you can shift the BFO by 40 Hz and correct your problem. Should you find your Dial Calibration off, you should start from the beginning step of setting the 4 MHz reference. If you need guidance in doing that as well as setting the filters/BFOs, you can find additional information and suggested procedures at my website http://w3fpr.qrpradio.com 73, Don W3FPR > -----Original Message----- > > I continue to struggle to get my KSB2 to sound as good as other > rigs. I've > heard other K2s on the air and know it's my individual problem. > > I was testing today on 7265 LSB trying out two different mikes - > Elecraft MD2 > and Ten Tec 706. The station listening said: > > - the Ten Tec has no lows and lower output > > - the MD2 sounds too bassy and muffled > > - the MD2 sounds fine if he tunes up 40 hz from my frequency > > Based on this, I recorded both from the audio on a separate > receiver. I agreed, > the MD2 sounded bad on frequency, but sounded normal if I tuned > up about 40 hz. > The Ten Tec had no lows and changing frequency made little > difference. But, it > took more voice to trip the VOX with the Ten Tec. > > Would this be due to my filter setup? > Will adjusting the OP1 filter bring my transmit frequency back? > Do I need to move the filter up or down? > Will changing KSB2 R14 from 1k to 2-3K help the Ten Tec mike > drive the KSB2? > > All help greatly appreciated. > > 73 de NA8M > John > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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