[HBR] HBR-??

[Bill Higgs]

Thanks for all the suggestions and comments! The tuning cap was =
successfully mounted by first locating and drilling the two large holes =
(for the dial and the shaft). Then, I placed masking tape in the =
approximate area of the four mounting bosses, then smudged a bit of =
stamp pad ink on the bosses before pressing the assembly against the =
front panel. Voila! - all four mounting holes cleanly marked. The actual =
mounting probably took 20 minutes; the rest of the time was helping the =
XYL fix this or that, running the kids to church, etc. At any rate, a =
shaft coupler, a 1/4 inch shaft stub, and an oversize 2-inch knob, and =
the cap tunes fairly smoothly.

The reason for trying the 6JH8 is that I have some. After reading Pat =
Hawker's note in Amateur Radio Techniques about the 6JH8 as a =
replacement for the 7360, and finding some on sale at $2 each, I bought =
3 to play with. I'll allow some room around the first mixer area so if I =
want to try one later, I can.

700kc tuning range: the original idea was to stick with the 1600kc IF of =
the HBR-16, so I had obtained a 1515kc crystal for the second conversion =
oscillator (2nd IF is 85kc). With a 1600kc IF you need to tune 5050 to =
5750 to cover all of 80 and 40 in an imaging design allowing for a 50kc =
overage on each end. This offsets the bands more than the 1700kc IF of =
the classical band imaging design.

As my usual oscillator design is to calculate L/C values based on range =
desired, measured min/max on the cap - then try what "looks right" and =
diddle with it until I get what I want. I may try a series cap: as I =
have three sections to play with (plus the internal trimmers), I do have =
several options.

Next weekend: power supply. The transformer I was planning to use is =
only rated for 70ma, which may be too low, especially if I draw =
additional current in the front end. I have another transformer salvaged =
from a Motorola 2-way which will give me 275v at somewhat more current. =
Problem is, it's bigger, so I'll have to check the fit (BEFORE drilling =
holes).

73,

Bill, NT4C

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