[R-390] Y501 Update

[Craig]

To The List:

Here we are back at the abode. The domestic chores are done & the lawn is
mowed. Time to play radio again. 
 
Today’s victim was the crystal from ICM. It is catalog #4122426, cost to my
door was $53.00 US dollarettes, and the holder type is HC51U, frequency
455KHz. Short version it works.

Fair Radio in Lima Ohio has used Z501 assemblies with crystal, less cover.
Price them if you must; your time, money, & radio. I decided to try a new
crystal and see if it works.

Plan “A” fell apart rapidly. Sticking the ¾ inch leads thru the crystal
holder was a no go. The holes in the holder are blind, they do not go all
the way thru to the underside of the IF deck. What to do, what to do? Plan
“B” was quickly devised. The leads on a CR-45/U holder are about ¼ inch in
length and 0.050 inches in diameter. The pins on the HC51U holder are about
¾ inches long and 0.030 inches in diameter. Back to the garage and retrieved
my metric caliper (it was handy). First cut the leads on the ICM crystal to
10mm in length. Next bend half (5mm) back over on itself. Don’t leave an
open loop at the bend. Use a needle nose vise grip to gently crush the bend.
The goal is to end up with leads about 5mm (1/4 inch) in length and 0.060
inches in diameter. 

The crystal holder accepted the non-Collins part. Oh Lord, is Charles
Steinmetz reading this or Art? (need to insert e-motion here, smile) The
proof is eating the pudding



.time to plug the Motorola into an outlet and
watch for magic smoke. Chapter Six in the Y2K R3 was used: 6.2.17 Crystal
Filter Neutralizing. The short version





I was able to get the .1KC & 1KC
positions to peak at 454.97KHz using a HP 8640B (no sticker traceable to
NIST). 

That is all for today! Chapter Three, paragraph 3.2.9.2 goes on to describe
the bandwidth for the .1KC & 1KC positions and resistors R502 & R503 for
adjustment. Gotta chew on this awhile. 

Regards,
Craig