[HBR] HBR-??

[hbr@mailman.qth.net]

In a message dated 1/31/04 6:46:57 PM Eastern Standard Time, 
Bill@LizCurtisHiggs.com writes:


> the plate design was far from linear; much closer to straight-line 
> wavelength than straight line frequency. Although I can use it to cover my range of 
> 5050-5750 in a High-C circuit, the linearity goes in the sewer.
> 
> Solutions:
> 
> 1. Live with it.
> 2. See if any of the folks on the list have a BC-454 or BC-455 tuning cap 
> they'd be willing to swap or sell (Anybody building up a Q-Fiver??)
> 

3. Put a fixed cap in series with the SLW variable to linearize the range
4. Tap the variable down on the coil for the same purpose.

Yes, you lose the use of the trimmers, but their range is fairly limited 
anyway.

Another trick I used in the Southgate Type 6 transceiver (20+ years ago!) was 

to use the classic ECO circuit (Hartley with a 6AU6A, screen grounded for RF, 
suppressor grounded directly), and put the grid circuit at half frequency, 
while the plate circuit consisted of a double-tuned bandpass circuit (pair of 
slugtuned coils).
Result was complete absence of pulling or chirp, very good stability and very 
linear dial from an SLW cap 

73 de Jim, N2EY




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