Regarding BFO trimmers and alignments.
The trimmer values and locations are C10 & C12 & C13 are each 4 - 20
pf. C16 is a 10 - 60. C18 is 1 - 6 pf.
As to alignment, I've found the procedure as published in the manual
must be followed in order as published and all steps must be done, even
if you do not operate or use one or more of the modes. There is
interaction between the adjustments which means you should go through
the sequence of steps 2 or 3 times. Also, be sure the radio is
"warm". The BFO crystals and components are affected by the ambient
temperature in the radio. The frequency will move around a bit thus
the highest accuracy you can attain will yield better results. It
takes patience to get it correct.
73
Bob, K4TAX
On 4/30/2018 8:15 AM, Barry N1EU wrote:
I believe there are three different values used: 4-20pf (qty 3), 1-6pf,
and 10-60pf. I believe the direct replacement I used was a Murata TZ03
series which are now obsolete. The trimmers are color coded and it
shouldn't be difficult to find replacements and you can always find them on
eBay as a last resort. Check the lead spacing - I believe it is 6mm.
This is a component that often fails over time, and is fairly easy to
replace.
73, Barry N1EU
On Mon, Apr 30, 2018 at 5:26 AM, Barry N1EU <barry.n1eu@gmail.com> wrote:
I replaced these a while back. I believe Mouser sells direct
replacements. I'll look through my old email and see if I can find the
invoice.
Barry N1EU
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On Sun, Apr 29, 2018 at 9:26 PM, Gary Hendricks <k4mt1950@charter.net>
wrote:
My schematic is so blurry I can tell for sure what the value of those
trimmer are. Looks like 4-20 PF but thats a guess.
Wanted to put some higher quality ones in. Do you have suggestions of
ones that have worked for you?
Gary K4MT
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