[DSP-10] SR105 Diode

[dewan]

Thanks a lot.  I noticed this already.  Both tx and rx would at 10v.  I 
will put it in.
Regards,
Rajiv, N2RD

On Saturday, July 27, 2002, at 06:16 PM, Richard Ewing wrote:

> Per Bob's web page here's the scoop:
> SR105" Diode When the DSP program is first started and before the PC 
> program is run, the DSP-10 can come up with BOTH transmit and receive 
> turned on. This sets up a loop that oscillates at full power! Very bad. 
> My DSP-10 shows about +16 or +17 dBm out. The happens because the shift 
> registers (U107, U108) come up uninitialized. The eventual solution 
> will be to program an EPROM that includes the setting of the shift 
> registers at DSP startup. Here is a work-around until you have an EPROM 
> version: Acquire a Schottky diode and solder the cathode (bar end) to 
> the junction of R132 and Q104-collector. Solder the anode (non-bar) end 
> to the junction of R130 & R131 (base of Q103). It must be a low barrier 
> voltage diode like the Schottky, but it can be either a rectifier or 
> small-signal type. I used a SR105 from Digi-Key, but I notice that 
> Radio Shack has 1N5817-1N5819 or 1N5820-1N5822 on special order status. 
> W7LHL suggested that a 1N34 type of germanium could work also. This 
> work-around prevents the 'transmit' from being enabled when 'receive' 
> is enabled. (Added 5 Sept 01, based on 27 Jan 00 reflector posting.)
>
>
> De KO7N  CN84ia
>
> A DSP-10 Enabled Station
>
>
> At 04:36 PM 7/27/2002 +0000, you wrote:
>> I have just about finished populating the DSP-10 board using the TAPR
>> kit.
>>
>> The only part left is through the hole diode SR105  "no designator".
>> Where does it go?
>>
>> Any help appreciated.
>>
>> Regards,
>> - -
>> Rajiv Dewan, N2RD
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