[1000mp] Inrad CW Mod Install

[Ian White, G3SEK]

Roger Cooke wrote:
>
>I have decided to do the W8JI mod so will have to sort out a day off!!!
>
It really isn't that bad - just lay off the full-strength morning 
coffee!

If this is an older MP, here are a few things to make it easier...

1. Build the little network of R1-R2-C1-C2 first. This network is very 
simple if you use miniature components on a scrap of perf-board, which 
can be stuck to the chassis beside the IF board (double-sided foam 
"Sticky Fixers").

If you don't have the miniature components, you have to find some more 
difficult and complicated way to mount them - so buy the parts that will 
let you do it the easy way:

R1 470k or 500k mini trimpot.
R2 10k mini trimpot
C1-C3  0.1uF miniature ceramic disk or multilayer, 0.1in lead spacing.

Do not include C3 on the board - see below.

2. Unscrew the fan from the PA unit, and lay them down separately on the 
bench next to the transceiver. You don't have to un-plug all the wires 
in order to do this. I can't remember exactly what you do need to 
un-plug, but it wasn't much.

If you're not confident about being able to put everything back together 
again, make notes or take digital photographs of where everything was, 
at each step. (Roger's right about giving yourself enough time, because 
re-assembly is easier to remember if you do it all in one session.)

3. Don't bother with the green wire from the RF board - that was only 
needed because Tom wanted to experiment with values for C3, and he found 
that 0.1uF was uncritical.

The rest of us can simply find the existing C1216 using Tom's 
photographs, bridge it with a 0.1uF cap, and then put the RF board back.

Make absolutely sure it really is C1216! There is only *one* component 
that *exactly* fits Tom's description and photographs. Double-check 
after you have soldered in C3.

4. The RC network will need a ground wire, so while the IF board is 
upside-down to solder a wire to C2148, also solder a ground wire to the 
edge of the board. Replace the IF board, connect the two wires to the RC 
network, and then stick the perf-board down to the chassis.

5. When tweaking R1 and R2 for minimum clicks, use SLOW keying so you 
can hear the separate clicks on make and break. Aim for the best balance 
between the two.


As I said, these hints are for the older MP. I'm not sure exactly how 
they play for the 1000D or the MkFives, but hope there might be 
something helpful for those models too.


-- 
73 from Ian G3SEK