[Milsurplus] mystery diode

[Glenn Little WB4UIV]

PD9047 is line number 31 on page 246

Glenn

On 9/15/2025 5:08 PM, Jim Whartenby via Milsurplus wrote:
> I was under the impression that Jacques has already done the research 
> and found that the diode in question is a silicon diode.  His suggestion 
> of a 1N4148 as a substitute appears to be a decent replacement with a 
> higher PIV and faster reverse recovery time.
> 
> Of course one can always do their own research and download the 1987 
> D.A.T.A diode book and make comparisons with what diodes they already 
> have on hand.  See:
> https://dn790008.ca.archive.org/0/items/bitsavers_dataInc198ion54_123911610/1987_DATA_Book_Diodes_Edition_54.pdf <https://dn790008.ca.archive.org/0/items/bitsavers_dataInc198ion54_123911610/1987_DATA_Book_Diodes_Edition_54.pdf>
> Jim
> 
> Logic: Method used to arrive at the wrong conclusion, with confidence.  
> Murphy
> 
> 
> On Monday, September 15, 2025 at 02:58:27 PM CDT, Brooke via Milsurplus 
> <milsurplus at mailman.qth.net> wrote:
> 
> 
> Hi Ray:
> 
> Do you have a way of measuring figuring out the voltage across the 
> diode.  For example if you know the meter sensitivity (for example: 1 mA 
> at full scale is 1 Volt) then you would know the diode voltage when the 
> meter was pinned at max reading.
> 
> I have some data on diodes that are being sold as "1N34", but most are 
> Schottky diodes.
> https://prc68.com/I/Xtal1800.shtml#Diodes 
> <https://prc68.com/I/Xtal1800.shtml#Diodes>
> 
> -- 
> Have Fun,
> 
> Brooke Clarke, N6GCE
> https://www.PRC68.com  <https://www.PRC68.com>
> axioms:
> 1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
> 2. Everybody, with no exceptions, holds false beliefs.
> 
> -------- Original Message --------
>> Date: Mon, 15 Sep 2025 01:04:08 +0000
>> From: Ray Fantini<RAFANTINI at salisbury.edu>  <mailto:RAFANTINI at salisbury.edu>
>> To: MMRCG<mmrcg at groups.io>  <mailto:mmrcg at groups.io>, Military Radio Collectors Association
>> 	<mrca at mailman.qth.net>  <mailto:mrca at mailman.qth.net>, List Milsurplus<milsurplus at mailman.qth.net>  <mailto:milsurplus at mailman.qth.net>
>> Subject: [Milsurplus] mystery diode
>> Message-ID:
>> 	<DM8P220MB04726E2DA952AB901FBAAB24B815A at DM8P220MB0472.NAMP220.PROD.OUTLOOK.COM>  <mailto:DM8P220MB04726E2DA952AB901FBAAB24B815A at DM8P220MB0472.NAMP220.PROD.OUTLOOK.COM>
>> 	
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Ok, so I have a very early AN/PRC-74 on the bench that has a shorted PD9047 diode (CR-15) that's used to develop the voltage for the tuning meter. the dam thing is very small and somehow don't think a 1N34 will take its place.
>> AI tells me that's a way obsolete part number and beyond its ability to come up with a replacement, anyone have any ideas? the tuning meter is somewhat important on the 74
>> This particular radio is serial number 606 and the PA deck is serial number 8! has strong output and in all other ways good.
>> you can see the circuit on page 186, figure 7-11 in the manual.
>>
>> Ray F/KA3EKH
> 
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-- 
-----------------------------------------------------------------------
Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIV            wb4uiv at arrl.net    AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI, FRA, NRA-LM    ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"