K3 Low Power FM
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Here is an update on my low power out on fm.
With all filter in place and with several checks on configuration and reloading the radio's firmware I had no success in getting out any more then 2 watts out max on FM. I removed the FM filter and replaced it with a .001 UF capacitor. I was successful in putting out any amount of power I selected on FM. I monitored the transmittion and it produces a very clean FM signal. So either there is something wrong with the filter or RF Board. Any comments (constructive please). Thanks 73 Dave KD1NA _______________________________________________ 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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> With all filter in place and with several checks on configuration and reloading the radio's firmware I had no success in getting out any more then 2 watts out max on FM.
> > I removed the FM filter and replaced it with a .001 UF capacitor. I was successful in putting out any amount of power I selected on FM. I monitored the transmittion and it produces a very clean FM signal. So either there is something wrong with the filter or RF Board. > > Any comments (constructive please). 1) Move an SSB filter to position #1 and see if Tx/Rx is nominal. This will tell you if the RF board is OK. 2) If it is, put the SSB filter back and re-install the FM filter. 3) If you have a sig gen or source of very stable amplitude signal, turn AGC off and use the AFV function and record the level in SSB mode coming through the SSB filter. Signal needs to have a good S/N but not be more than S9+5 or so to be sure hardware AGC doesn't interfere with the measurement. 4) advance to the dBV position on the VFO B display and you'll see it bobbling around +/- 0.1 or 0.2 dB. 5) Enable the FM filter for SSB and then tap XFIL to switch to the FM filter. You'll then see the relative attenuation of that filter vs your SSB filter. In my case, the 2.8kHz, 6.0 kHz and 13.0 kHz filters are all within a tiny fraction of a dB of each other at an audio pitch of several hundred Hz and a good S/N . Sig Gen was at -80 dBm, or 22 uV. --- The AFV and dBV function of the K3 makes it possible to do some pretty accurate measurements. You can determine MDS, see filter attenuation and be sure your filter configuration loss compensation values are in fact correct instead of guessing, etc. 73, Lyle KK7P _______________________________________________ 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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At 10:23 PM 5/25/2008, Lyle Johnson wrote:
<snip> >The AFV and dBV function of the K3 makes it possible to do some >pretty accurate measurements. You can determine MDS, see filter >attenuation and be sure your filter configuration loss compensation >values are in fact correct instead of guessing, etc. I guess I had better start reading the manuals. Which one tells me how to do the above? Jerry W4UK _______________________________________________ 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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Jerry Flanders wrote:
> At 10:23 PM 5/25/2008, Lyle Johnson wrote: > <snip> >> The AFV and dBV function of the K3 makes it possible to do some pretty >> accurate measurements. You can determine MDS, see filter attenuation >> and be sure your filter configuration loss compensation values are in >> fact correct instead of guessing, etc. > > I guess I had better start reading the manuals. Which one tells me how > to do the above? VFO B Alternate Displays is a topic on page 34 of the Owner's Manual. Not much info there. Basically, you operate it as I described: get your reference, in AFV, then switch to dBV. If AGC is off, you'll get absolute relationships as long as the hardware AGC is not activated. On the other hand, with AGC on you can determine what the AGC SLP (slope) control does, etc. It's pretty much up to your imagination... 73, Lyle KK7P _______________________________________________ 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 KK7P
Thanks Lyle,
I removed all my filters and installed the 2.7 k filter in port 1 (in place of the FM filter). after reconfiguring the K3 the rig worked very well with SSB and CW so the RF board is good. The only thing I need to do is get a working FM filter from Elecraft. Right now I got a .001 capacitor in the place of the FM filter and this gives me the ability to at least work FM until I can get the situation fixed. I have some equipment that can generate a signal but I have to read up on the AFV function. Then I will reinstall the FM filter and try your tests I think I will know what I will find because with the capacitor in place of the FM filter lets me output any power I ask for. Thanks again for your good advice and 73 Dave KD1NA ----- Original Message ----- From: "Lyle Johnson" <[hidden email]> To: "Dave & Jeanne Robertson" <[hidden email]> Cc: "Elecraft" <[hidden email]> Sent: Sunday, May 25, 2008 10:23 PM Subject: Re: [Elecraft] K3 Low Power FM >> With all filter in place and with several checks on configuration and >> reloading the radio's firmware I had no success in getting out any more >> then 2 watts out max on FM. >> >> I removed the FM filter and replaced it with a .001 UF capacitor. I was >> successful in putting out any amount of power I selected on FM. I >> monitored the transmittion and it produces a very clean FM signal. So >> either there is something wrong with the filter or RF Board. >> >> Any comments (constructive please). > > 1) Move an SSB filter to position #1 and see if Tx/Rx is nominal. This > will tell you if the RF board is OK. > > 2) If it is, put the SSB filter back and re-install the FM filter. > > 3) If you have a sig gen or source of very stable amplitude signal, turn > AGC off and use the AFV function and record the level in SSB mode coming > through the SSB filter. Signal needs to have a good S/N but not be more > than S9+5 or so to be sure hardware AGC doesn't interfere with the > measurement. > > 4) advance to the dBV position on the VFO B display and you'll see it > bobbling around +/- 0.1 or 0.2 dB. > > 5) Enable the FM filter for SSB and then tap XFIL to switch to the FM > filter. You'll then see the relative attenuation of that filter vs your > SSB filter. > > In my case, the 2.8kHz, 6.0 kHz and 13.0 kHz filters are all within a tiny > fraction of a dB of each other at an audio pitch of several hundred Hz and > a good S/N . Sig Gen was at -80 dBm, or 22 uV. > > --- > > The AFV and dBV function of the K3 makes it possible to do some pretty > accurate measurements. You can determine MDS, see filter attenuation and > be sure your filter configuration loss compensation values are in fact > correct instead of guessing, etc. > > > 73, > > Lyle KK7P > _______________________________________________ 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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Dave & Jeanne Robertson wrote:
> do is get a working FM filter from Elecraft. Right now I got a .001 > capacitor in the place of the FM filter and this gives me the ability to > at least work FM until I can get the situation fixed. I'd be surprised if it was legal to transmit to air in this configuration. I would have thought you would be putting out too much power at the DSP IF image frequency to meet the minimum necessary bandwidth requirement. You may also be generating significant power at alias frequencies, which might mean you are transmitting excess power beyond the band edge. -- David Woolley "The Elecraft list is a forum for the discussion of topics related to Elecraft products and more general topics related ham radio" List Guidelines <http://www.elecraft.com/elecraft_list_guidelines.htm> _______________________________________________ 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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