Hi Russ, Yes i did and it was a marvelous hack in the best sense of the word, It was fascinating to see how this actually worked, it of course is no longer necessary and I have removed it in favor of protecting the A1 assembly fully within the chassis.
My 117A is a Prefix 438A unit and my manual covers 525A and below. I'm still debating whether to use a AMRAD antenna and disconnect the +35 from the antenna (by installing a jumper block for reversability) or find the proper 10509A loop antenna for authenticity. I have been offered a amp assembly for the antenna by another member so I have thought about fabricating the actual loop assembly but I do not have dimensions for the loop itself which looks to be center tapped which also would the tube which bisects the loop. I bought this a decade ago and was only able to find a manual recently always kept it because I knew how rare this unit is. Right now it's been recapped (electrolytics) and I have replaced the chassis mount transistors BTW a NTE121 will replace the TO-3 pass transistor if that has given up the ghost. RIght now I am going through the power supply board A9 and replacing the resistors many of which have changed value after physically rebuilding the PCB which had a 1/2" hole burned in the area of R2-4. One of the challenges of recapping is that electrolytics are now much smaller for equivalent ratings so a lot of teflon sleeving has been used to prevent potential short circuits. So much fun to be had with this stuff! - Regards Scott On Thu, Sep 11, 2008 at 10:50 AM, <[EMAIL PROTECTED]> wrote: > > Scott, > > Good luck on the rare 117A. > > Did you get my e-mail with attachment containing the pages of the manual for > your updated unit? > > Russ > > -----Original Message----- > From: Scott McGrath <[EMAIL PROTECTED]> > To: [EMAIL PROTECTED] > Sent: Wed, 10 Sep 2008 12:42 pm > Subject: Re: [time-nuts] Odd HP 117A configuration > > > > Hi, Ross > > Please - It would be interesting to see how this worked. From the > date codes on the components my 117A was built in late 1964 - date > codes on conversion module date from 1968. As Tom noted it is a > interesting historical footnote from use of the atomic timescale to > UTC timescale with leap seconds. And now due to the influence of > embedded device manfacturers who want 'cheap n cheerful' firmware we > are now discussing doing away with leap seconds. Interesting how > the pendulum of historical trends oscillates. > > Right now the 117A is having all the electrolytics replaced while I am > reconstructing the PS module trace by trace > > - Scott > > > > On Wed, Sep 10, 2008 at 7:43 AM, <[EMAIL PROTECTED]> wrote: >> >> Scott, >> I had a chance to look at my HP 117A manual last night and saw that > > your >> >> configuration is described there. If it is not described in the HP > > 117A >> >> manual that you have, would you like me to copy those pages and send > > them to >> >> you as an attachment? >> Russ >> >> >> -----Original Message----- >> From: Scott McGrath <[EMAIL PROTECTED]> >> To: [email protected] >> Sent: Mon, 8 Sep 2008 3:50 pm >> Subject: [time-nuts] Odd HP 117A configuration >> >> >> >> All, >> >> I purchased a 117A at a hamfest years ago and am just now looking into >> it. This 117A is a bit different from the ones in the manual and >> in pictures up on the web as it incorporates a telechron reduction >> motor installed in fthe area in front of the TRF module harness >> connector. Had not looked at this unit much as I did not have a >> manual which I now have as the power supply board (A9) had a charred >> hole blown in it. The TRF module does not insert fully into the >> chassis due to the presence of the clockwork module. Interestingly >> enough the clockwork looks like HP installed it or someone did a VERY >> good job. Does anyone know what this clockwork is intended for? >> >> I am now rebuidling the circuit board with glass filled epoxy (West >> Brothers + microsphere filler) with a mold/retaining dam made from >> silicone rubber. >> >> Also back when I was at UNH when I was young and foolish a HP 117A was >> my introduction to precision timing as Jim Williams in Demerrit Hall's >> maintained the frequency standard which consisted of a HP117A and a HP >> 5245M frequency counter along with a decade worth of recorder output. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
