Thanks Don I am borrowing a military surplus RF voltmeter with probe this afternoon. I was thinking the crystal also. Not many parts in the circuit.
Thanks for the pointers. 73 Dave wo2x Sent from my iPad > On May 20, 2020, at 2:36 PM, Don Wilhelm <[email protected]> wrote: > > There is the possibility that the 40 meter crystal has low activity. > Check the RF voltage at pin 4 of P1 on the band board. You should read 70mV > or more with an RF Probe or 200mV+ peak to peak if using a 'scope with a 10X > probe. > > A good working K1 will develop at least 5 watts. > Make up an RF probe if you don't have one. It does not have to be fancy, > just stick the component leads through a piece of cardboard and solder the > leads together. You need a 1N34 diode (not a silicon diode) Elecraft does > have a kit. > > 73, > Don W3FPR > >> On 5/20/2020 1:35 PM, [email protected] wrote: >> Hi Don >> >> I have done that using the Marconi for RX, then touching up for TX. I >> understand 40 is a combo of 30 & 40 settings. After carefully retuning (done >> it several times) the best I can get on 40 is about 60 to 75 mW. 30 makes >> better than 2 watts. The menu for power out is set to 2.0 on 40. Receive >> sensitivity is 10 to 15 dB down from 30 meter receive. >> >> I read that the windings on T3 and T4 are critical. I have counted the turns >> and verified which side #1,2,3 and 4 are coming off the core. Both T3 and T4 >> appear to be fine. There is enough wire left over in the box the radio was >> in so I can rewind T3 or T4. From what I see on the schematic T4 would most >> likely be the suspect (if it is the transformer.) >> >> I am going to borrow an RF Power meter with probe and check 30 vs 40 meter >> readings on the Premix in & out and the RF filter in & out. That will >> greatly help pinpoint the issue. >> >> 73 >> Dave wo2x >> >> >> -----Original Message----- >> From: Don Wilhelm <[email protected]> >> Sent: Wednesday, May 20, 2020 11:39 AM >> To: [email protected]; [email protected] >> Subject: Re: [Elecraft] K1-4 low power and poor receive on 40 meters >> >> Dave, >> >> Refer to the K1FL4 instructions and re-tune the trimmers on the filter >> board. They MUST be done in the proper band sequence - 30 meters before >> 40m, 15m before 20m. The PreMixer portion is usually the most critical for >> power output. >> >> 73, >> Don W3FPR >> >>> On 5/20/2020 11:20 AM, [email protected] wrote: >>> Hi All, >>> >>> >>> I am going to sell a K1-4 (4 band 40, 30, 20, 15) for the estate of my >>> Elmer. In testing the radio I found 40 meters is about 15dB less >>> sensitivity than 30 and power out about 75 mW. I have double checked >>> the values of components on the filter board to ensure they are >>> correct and installed correctly. I also checked T3 and T4 which can >>> cause issues on 40. T3 has 23 turns on the secondary with three turns >>> on the primary. T4 has 24 turns on secondary and two turns on primary. >>> Another symptom is the CH trimmer cap seems to be at one end of tuning >>> range (not seeing double peak). >>> >>> >>> Note - the radio does not have the ATU option and 30 meters is set for >>> 10.1 MHz and not 10.0 (double checked crystals). >>> >>> >>> >From what I can measure so far the relays seem to be working "as designed". >>> When I switch from 15 meters to 40 meters I can see the pulses to the >>> relays to switch them (latching relays. I did notice in the 4 band >>> filter manual it says K6 relay is not active on 40 but I do see it >>> active and looking at the schematic K6 switches between 15/20 >>> operation and 30/40 so I think there is a typo in the filter board manual >>> at the bottom of page 23. >>> >>> >>> I am using a Marconi service monitor for testing. I have not built an >>> RF probe yet and hoping someone has seen this symptom before. I would >>> like to get the K1 fully operational as the proceeds are going to my >>> Elmer's widow 100% >>> > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
