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K1-4 low power and poor receive on 40 meters

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Dave wo2x

K1-4 low power and poor receive on 40 meters

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%

Thanks for reading!

Dave wo2x

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Don Wilhelm

Re: 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, [hidden email] 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:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Dave wo2x

Re: K1-4 low power and poor receive on 40 meters

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 <[hidden email]>
Sent: Wednesday, May 20, 2020 11:39 AM
To: [hidden email]; [hidden email]
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, [hidden email] 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%
>

Don Wilhelm

Re: K1-4 low power and poor receive on 40 meters

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, [hidden email] 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 <[hidden email]>
> Sent: Wednesday, May 20, 2020 11:39 AM
> To: [hidden email]; [hidden email]
> 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, [hidden email] 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%
>>

Dave wo2x

Re: K1-4 low power and poor receive on 40 meters

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 <[hidden email]> 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, [hidden email] 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 <[hidden email]>
>> Sent: Wednesday, May 20, 2020 11:39 AM
>> To: [hidden email]; [hidden email]
>> 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, [hidden email] 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%
>>>
>

Dave wo2x

Re: K1-4 low power and poor receive on 40 meters

In reply to this post by Don Wilhelm

Hi Don,

You nailed it. No output from the 15 MHz crystal. The other three bands are showing good output. I checked the relays K1 and K2 to verify each has pins 3 to 4 conductivity when on 40 meters (set radio to 40 meters, power down, and remove filter board since relays are latching. One side of crystal checks good to ground and the other side checks good to P1 pin 4.

Ordered new 15 MHz crystal from Elecraft.

Thanks for the advice. Once I got the RF volt meter it took a few minutes to find the problem.

73 and thanks again!
Dave wo2x

-----Original Message-----
From: Don Wilhelm <[hidden email]>
Sent: Wednesday, May 20, 2020 2:37 PM
To: [hidden email]; [hidden email]
Subject: Re: [Elecraft] K1-4 low power and poor receive on 40 meters

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, [hidden email] 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 <[hidden email]>
> Sent: Wednesday, May 20, 2020 11:39 AM
> To: [hidden email]; [hidden email]
> 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, [hidden email] 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%
>>