[Elecraft] Temp Stability Mod

[Wayne Burdick]

Hi Jim,

Thanks for the report.

R19 extends the PLL reference oscillator range by 0.5-1.5 kHz if necessary. It
can't hurt to add it, but you probably don't need it if you already had adequate
tuning range with one crystal. If you do add it, you'll have to do CAL PLL again.

The original value of R19 was 220 ohms -- my mistake. It should have been 2.7 k.
(1.8 to 3.3 k will work.) This has been corrected in all documentation now.

73,
Wayne


James Brown wrote:
> 
> Gentlemen,
> 
> I have completed the temp stability mod purchased from Elecraft, and have
> compiled the following information:
> 
> Time        Freq        Delta
>  (Min)        (Hz)          (Hz)
> 0               750            0
> 5               745           -5
> 10             740         -10
> 15             732         -18
> 20             726         -24
> 25             722         -28
> 30             717         -33
> 35             713         -37
> 40             708         -42
> 45             703         -47
> 50             702         -48
> 55             698         -52
> 60             696         -54
> 
> Measurements were made on K2 #2535 in CW mode, 10Mhz WWV carrier producing
> tone of 750Hz at 0 minutes from a cold start, using Spectrogram 7.2.
> Spectrogram resolution was +- 1.3Hz. This mod improved the received
> frequency stability on the order of 50% over the stated Elecraft
> specifications.
> 
> I reviewed this mod as posted on N0SS's site and found a difference between
> that posting and the printed material received from Elecraft with the mod
> kit. Figure 1 on Tom's posting shows R19 added across pins 7 and 8 of RP2.
> The diagram from Elecraft is cropped so that RP2 is not shown, and makes no
> mention of R19.
> 
> Should R19 be added, and if so, what is it's purpose?
> 
> K2'in away.....
> 
> Jim Brown, K5JAZ
> 
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