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, rocke...@gmail.com 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 <donw...@embarqmail.com>
Sent: Wednesday, May 20, 2020 11:39 AM
To: rocke...@gmail.com; elecraft@mailman.qth.net
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, rocke...@gmail.com 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%
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