[GreenKeys] Model 33 keyboard spring issue

[Richard Knoppow]

     There is a military handbook for the RCA DR-89 diversity receiver 
AKA Navy RDM. This is a triple diversity receiver using modified RCA 
AR-88 receivers. It is set up mainly for CW, the output uses a tone 
generator to send a CW signal over wires. There is a note on the 
schematics and I think also in the text about a frequency shift 
converter or attachment but I have never found any details of it. 
Presumably this was for Morse and not RTTY but I have no further 
information.  The advantage of triple diversity is that it improves the 
fading margin by something like 30db. Going to FSK would, also 
presumably, reduce necessary power for a given circuit reliability even 
more. It would be interesting to know more.

On 1/3/2017 2:19 PM, Wayne Durkee wrote:
> Doug,
>
> Glad you got CR or Bell issue fixed,.
>
> Also, the leaf spring issue is common. There are actually two leaf
> springs under the kybd, but replacing the printer will cause this
> problem easily. When replacing the printer, your eye should be on the
> Here Is tab.
>
> Well done!
>
> A little more time and you will be an expert on these 33's.
>
> 73,
>
> Wayne
>
>> On January 3, 2017 at 3:52 PM "Jones, Douglas W"
> <douglas-w-jones at uiowa.edu> wrote:
>>
>>
>> I noticed that the CR and LF keys on my 33, and also the =- key were
> getting sticky. That is, when you pressed one of them down, it stayed
> down and didn't spring back up. Pressing any other key would pop it up,
> but obviously, something was wrong with the springs that push these keys
> back.
>>
>> There's a big leaf spring assembly on the bottom of the 33 keyboard,
> all stamped out of a single bit of blued spring steel, with one finger
> to push up on each key. While I had the TU out to fix the problem with
> the end-of-line bell, I took the time to lift the keyboard and see what
> the problem was.
>>
>> It turns out that, every time you re-install the TU, there's a risk
> that the plastic paddle that engages with the "here-is" key will scrape
> sideways over the spring assembly while all your attention is on
> engaging the H plate that links the unversal lever to the transmitter
> distributer. As it scrapes sideways, it can push the ends of the springs
> off of the bottoms of the key levers.
>>
>> So, after you've installed the TU, if you find that CR, =- or LF are
> sticking down, what do you do?
>>
>> Solution 1: Take out the TU and possibly even the UCC so you can pull
> the keyboard and then use your fingernails to pop the springs back into
> position, then reinstall the TU, with the risk that you'll brush the
> springs out of place again. Repeat until successful.
>>
>> Solution 2: Fortunately, the 3 keys that are at greatest risk of
> having their springs brushed to the side so they stick down can be fixed
> from above. Look down into the space between the back of the keyboard
> and the front of the TU, and you'll find a cutout in the back-plate of
> the keyboard that lets you see 3 holes in the keyboard base. A finger
> from each of the 3 keylevers in question pushed down through one of
> these holes, and from below, the leaf springs push up on those keylevers.
>>
>> If the leaf springs have been brushed to the side when you installed
> the TU, the result is that the spring will be caught on the side of the
> keylever finger instead of pushing up on the keylever. Poke down beside
> the keylever with a jeweler's screwdriver, and you can dislodge the leaf
> spring from the side of the finger. It'll pop immediately back into
> place. Problem solved.
>>
>> Doug Jones
>> jones at cs.uiowa.edu
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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL