No TX Power Out
Locked
 
|
Hi,
This is my second K2 build Just got to Alignment and Test Part III and can't get RF out. Receiver tests OK Supply is 13.8V 8V regulator gives 7.59V 5V regulator gives 4.99V AGC threshold is 3.6V (highest voltage I can get) - same as first K2 built. No measurable power out - display says 0.1 W in Tune mode Indicated current: 220mA - RX 520mA - TX Indicated Voltage: 13.4V - RX 13.2V - TX 4.97V on VPWR at pin 2 of U8 with key down RF detector components and soldering checked OK Basic Voltage Checks: D6 anode goes to 240mV on TX D7 anode goes to 7.49V on TX I am having difficulty with the Mixer, Buffer, Band Pass Filter, T-R Switch and subsequent tests. I have built the RF probe and it works OK. All of the measurements for the tests above show a trace of voltage on switching to TX which then disappears. Problem in the T-R Switch or am I missing something obvious? Any help appreciated. David EI9EUB ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
|
|
David,
When making the Transmit Signal Tracing tests, stop at the *first* place where the RF voltage is substantially *lower* than the expected value. That stage has inadequate output. In other words, if the transmit mixer has low output, one can expect low output at all points in the transmit chain beyond the mixer - even though those following stages may be working fine. Since your first failure stage seemed to be the transmit mixer, check all components shown around U10 on the schematic. Be certain you are getting enough RF voltage from the VCO to U10 pin 6 (0.5 volts minimum). Additionally, you must have a good signal into U10 pin 1 - check the amount of RF voltage at TP2, then both sides of C167 and finally U10 pin 1. There should be only a small dropoff of the BFO signal as you progress along that path. Use the level at TP2 for the reference level. 73, Don W3FPR David Gilmartin wrote: > Hi, > > This is my second K2 build > > Just got to Alignment and Test Part III and can't get RF out. > > > > Receiver tests OK > > Supply is 13.8V > > 8V regulator gives 7.59V > > 5V regulator gives 4.99V > > AGC threshold is 3.6V (highest voltage I can get) - same as first K2 > built. > > > > No measurable power out - display says 0.1 W in Tune mode > > Indicated current: > > 220mA - RX > 520mA - TX > > Indicated Voltage: > > 13.4V - RX > 13.2V - TX > > 4.97V on VPWR at pin 2 of U8 with key down > > RF detector components and soldering checked OK > > > > > Basic Voltage Checks: > > D6 anode goes to 240mV on TX > > D7 anode goes to 7.49V on TX > > > > > I am having difficulty with the Mixer, Buffer, Band Pass Filter, T-R > Switch and subsequent tests. > > I have built the RF probe and it works OK. All of the measurements for > the tests above show a trace of voltage on switching to TX which then > disappears. > > > > > Problem in the T-R Switch or am I missing something obvious? > > Any help appreciated. > > David > EI9EUB > > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
|
|
Thanks Don,
Problem was with D36 (SMT1B) - used pad 1 and 2 not 2 and 3 RTFM! 73 David EI9EUB On 20 May 2009, at 17:38, Don Wilhelm wrote: > David, > > When making the Transmit Signal Tracing tests, stop at the *first* > place where the RF voltage is substantially *lower* than the > expected value. That stage has inadequate output. In other words, > if the transmit mixer has low output, one can expect low output at > all points in the transmit chain beyond the mixer - even though > those following stages may be working fine. > > Since your first failure stage seemed to be the transmit mixer, > check all components shown around U10 on the schematic. Be certain > you are getting enough RF voltage from the VCO to U10 pin 6 (0.5 > volts minimum). Additionally, you must have a good signal into U10 > pin 1 - check the amount of RF voltage at TP2, then both sides of > C167 and finally U10 pin 1. There should be only a small dropoff of > the BFO signal as you progress along that path. Use the level at > TP2 for the reference level. > > 73, > Don W3FPR > > David Gilmartin wrote: >> Hi, >> >> This is my second K2 build >> >> Just got to Alignment and Test Part III and can't get RF out. >> >> >> >> Receiver tests OK >> >> Supply is 13.8V >> >> 8V regulator gives 7.59V >> >> 5V regulator gives 4.99V >> >> AGC threshold is 3.6V (highest voltage I can get) - same as first >> K2 built. >> >> >> >> No measurable power out - display says 0.1 W in Tune mode >> >> Indicated current: >> >> 220mA - RX >> 520mA - TX >> >> Indicated Voltage: >> >> 13.4V - RX >> 13.2V - TX >> >> 4.97V on VPWR at pin 2 of U8 with key down >> >> RF detector components and soldering checked OK >> >> >> >> >> Basic Voltage Checks: >> >> D6 anode goes to 240mV on TX >> >> D7 anode goes to 7.49V on TX >> >> >> >> >> I am having difficulty with the Mixer, Buffer, Band Pass Filter, T- >> R Switch and subsequent tests. >> >> I have built the RF probe and it works OK. All of the measurements >> for the tests above show a trace of voltage on switching to TX >> which then disappears. >> >> >> >> >> Problem in the T-R Switch or am I missing something obvious? >> >> Any help appreciated. >> >> David >> EI9EUB >> > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
«
Return to [K2]
|
1 view|%1 views
| Free forum by Nabble | Edit this page |