[Elecraft] How do I know if my K2 has BFOMDKT installed?

[Dave Van Wallaghen]

Correct Andrew. Even if it is a 10K RP you'll still want to add R19.

I just got done fully upgrading a field test K2 here and had 100K stuck 
in my head. But it is the same whether 100K or 10K RP's.

73,
Dave, W8FGU


On 7/22/2022 10:52:06 AM, "Andrew Moore" <andrew.nv1b at gmail.com> wrote:

>Hi Dave -
>
>My s/n 892 currently has RP2 = 10k, not 100k. Does the 2.7k still need 
>to be added across pins 7 and 8?
>
>From the PLL Ref Upgrade kit docs (E850138), it sounds like it might 
>need to be added regardless of 10k/100k, as the first step below 
>doesn't differentiate, while the next step does:
>
>[_] If your K2 serial number is lower than 3000, make sure you have 
>installed the BFO modification (BFOMDKT). One of the items supplied in 
>this kit is a 2.7-k resistor. This resistor, designated R19, must be 
>soldered across pins 7 and 8 of resistor network WP2 (in the PLL area).
>
>[_] If you have an older K2 (early revision A for Field Test), you may 
>have a 100k resistor network installed at RP2, which is in the VCO 
>area. If so, you'll need to solder two 10k to 12k resistors across RP2, 
>which can be difficult...
>
>Thanks,
>-Andrew NV1B
>..
>
>
>On Fri, Jul 22, 2022 at 9:30 AM Dave Van Wallaghen <dave at w8fgu.com> 
>wrote:
>>Hi Andrew,
>>
>>Yes, place that 2.7KΩ resistor across RP2 pins 7 & 8. This resistor is
>>on the output of U6A to drive the varactor diodes in the PLL 
>>Osciillator
>>circuit. It was changed to 2.7K in Rev B. In Rev A it was 100K and 
>>part
>>of RP2, so you are just placing a 2.7k resistor in parallel with the
>>100K on RP2 P& and P8. I believe the change was to help add stability 
>>to
>>the PLL Oscillator circuit.
>>
>>73,
>>Dave, W8FGU
>>
>>
>>On 7/21/2022 11:04:58 PM, "Andrew Moore" <andrew.nv1b at gmail.com> 
>>wrote:
>>
>> >I just installed the temperature compensated PLL reference upgrade 
>>kit on
>> >my K2 #892.
>> >
>> >From everything I can see, this rig (which I bought used) has been 
>>brought
>> >up to date in almost every way.
>> >
>> >One step in the assembly instructions says that for S/N < 3000, make 
>>sure
>> >I've installed the BFOMDKT upgrade, and that the kit includes a 2.7k
>> >resistor R19 that's soldered across pins 7 and 8 of RP2 (according to
>> >document "Upgrading the Elecraft K2 to Revision B").
>> >
>> >My RP2 (10K) has no resistor across any pins. However, I do have L33
>> >upgraded to the prewound 41 uH inductor, which I think was part of 
>>the
>> >BFOMDKT.
>> >
>> >Should I be adding 2.7k across pins 7 and 8? Is there any reason this 
>>would
>> >not have been done as part of the BFOMDKIT upgrade?
>> >
>> >Thanks,
>> >-Andrew NV1B
>> >..
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