[ARC5] 10 meter BC-454 - Drift.

[Brian Clarke]

Hello Ken,

How did you compensate for the inherent drift of the HP 8640B? I have two 
that both drift at almost the same rate.

Why did you have the BFO on? The drift of which oscillator were you 
tracking?

And 28.5 - 28.476426 says 23.574 kHz. That kind of drift would be OK on AM 
but not on CW or SSB.

73 de Brian, VK2GCE.

On Friday, March 08, 2013 8:04 AM, you said:.


> Conditions: Initial frequency: 28.500 MHz. BFO: On. Main tuning; 
> untouched. Power: Off
> since last night. HP-8640B not turned off since yesterday.
>
> Result: Drifted 16 KHz lower within 5 minutes. 30 minutes later, drifted 
> an additional 7.5 KHz.
> lower. 60 minutes later, no substantial change.
>
> Final frequency: 28,476,426 Hz
>
> Total drift: Approximately 26.5 KHz.
>
> I suppose that considering that the receiver is now operating at 10 times 
> its original operating
> frequency with home-made coils, and no attempt at temperature 
> compensation, this result is
> "acceptable".
>
> Would anyone here wish me to begin again, and take readings more often in 
> order to plot a
> graph?
>
> I think it is unnecessary...
>
> The receiver is, to my mind, not all that stable: every time a piece of 
> equipment in the home
> starts and stops, I can hear the receiver change frequency. The BFO pitch 
> "burps".
>
> The power supply is completely unregulated. I might try a regulated supply 
> to see if that
> helps. It probably would.
>
> Ken W7EKB