I bought from Little Diode around 10 years ago, a variety of RF transistors similar to and including 2N3866 with the specific intention of comparing them for suitability in LF/HF active antennas. However all the devices they supplied looked to have been rebranded from the same generic stock, I'd had some experience of this in the past but it still took a LOT of effort before I finally got past the evasive responses and they admitted this was true, which of course made any comparison pretty pointless. They didn't refer to them as "generic", can't remember what expression they did use now in their initial responses but remember it wasn't something I'd come across before, but there were certainly no indications at the point of sale that these weren't original manufacturer's branded stock. Such rebranding and subterfuge was common amongst some at least of the aftermarket electronic valve suppliers in the late 1960s, a bog standard device going in one door could come out another as the ruggedised version, for example, and much more expensive, and it would seem similar practices lived on. I wouldn't touch them again with the proverbial barge pole, although I have to accept others may have had better experience. Regards Nigel GM8PZR In a message dated 31/10/2014 10:49:12 GMT Standard Time, david.partridge@perdrix.co.uk writes: I might be worth asking eBay vendor LittleDiode, they are the eBay shop for LittleDiode Components ... Regards, David Partridge -----Original Message----- From: volt-nuts [mailto:volt-nuts-bounces@febo.com] On Behalf Of Charles Black Sent: 31 October 2014 00:09 To: volt-nuts@febo.com Subject: [volt-nuts] Solartron 7081 With Bad WR057 Diode My Solartron 7081 has a bad WR057 diode that needs to be replaced. It's a three terminal device that looks like two silicon diodes in parallel. It was making the meter read about 10.1V with a 10V input. Luckily it was temperature sensitive and was easy to find with freeze mist. Removal caused a shorted input to be about 2.5 microvolts high and a little noisy. I've not been able to find this device on the internet but thought that someone here might have seen this thing before. Charlie _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.

Littlediode is no more. The only other ebay seller has been caught re-branding and selling used as new. I have been looking at pico amp reverse cxurrent diodes that are still being sold and have not founds any that favorably compare with the DPAD1. The DPAD1 is only being sold by one source as far as my research has gone today. It is Linear Systems/micross. They are a bit dear at $4.35US each but could be used to upgrade the 7081's performance a small amount. I was ordering them last night and all was going well until they overcharged ($20US) for UPS ground. It's hard to trust a company that does that! David, I want to thank you for your 7081 information on your web site. I used the troubles you had with your 7081 repair as a starting point for my first repair and it saved me a lot of time. Nigel, thanks for letting me know aboutlittlediode and your experience with them. Charlie On 10/31/2014 4:30 AM, Nigel Clarke via volt-nuts wrote: > I bought from Little Diode around 10 years ago, a variety of RF > transistors similar to and including 2N3866 with the specific intention of comparing > them for suitability in LF/HF active antennas. > However all the devices they supplied looked to have been rebranded from > the same generic stock, I'd had some experience of this in the past but it > still took a LOT of effort before I finally got past the evasive responses > and they admitted this was true, which of course made any comparison pretty > pointless. > > They didn't refer to them as "generic", can't remember what expression they > did use now in their initial responses but remember it wasn't something > I'd come across before, but there were certainly no indications at the point > of sale that these weren't original manufacturer's branded stock. > > Such rebranding and subterfuge was common amongst some at least of the > aftermarket electronic valve suppliers in the late 1960s, a bog standard device > going in one door could come out another as the ruggedised version, for > example, and much more expensive, and it would seem similar practices lived > on. > > I wouldn't touch them again with the proverbial barge pole, although I have > to accept others may have had better experience. > > Regards > > Nigel > GM8PZR > > > > > > In a message dated 31/10/2014 10:49:12 GMT Standard Time, > david.partridge@perdrix.co.uk writes: > > I might be worth asking eBay vendor LittleDiode, they are the eBay shop > for LittleDiode Components ... > > Regards, > David Partridge > -----Original Message----- > From: volt-nuts [mailto:volt-nuts-bounces@febo.com] On Behalf Of Charles > Black > Sent: 31 October 2014 00:09 > To: volt-nuts@febo.com > Subject: [volt-nuts] Solartron 7081 With Bad WR057 Diode > > My Solartron 7081 has a bad WR057 diode that needs to be replaced. It's a > three terminal device that looks like two silicon diodes in parallel. > It was making the meter read about 10.1V with a 10V input. Luckily it was > temperature sensitive and was easy to find with freeze mist. Removal caused > a shorted input to be about 2.5 microvolts high and a little noisy. I've > not been able to find this device on the internet but thought that someone > here might have seen this thing before. > > Charlie > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > >

Charlie, Calogic appears to sell directly, they may even send you a sample. I guess it wouldn't hurt to ask. Todd

As a matter of interest which particular diode is causing these symptoms? On 31 October 2014 15:18, Todd Micallef <tmicallef@gmail.com> wrote: > Charlie, > > Calogic appears to sell directly, they may even send you a sample. I guess > it wouldn't hurt to ask. > > Todd > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.

It's D110 on PCB6. After removing D110 the 7081 read about +2.5 microvolt with the input shorted with an external jumper. When I shorted the HI amp input with the MYTCHETT test point the 7081 read about -1.0 microvolt with low noise. I expect that the D101 (DPAD1) is the culprit. Presently: Compared to my ancient HP3458a (last calibrated in 1990 and still on CAL 1) the 7081 reads about 10 microvolts higher. The 7081 reads about 25 microvolts higher than my not quite as ancient Ag3458a. The Datron 4910 was calibrated by Fluke in March of 2012. I'm going to change out temperature sensitive parts and leaky parts and remeasure. Charlie At 10V input the 7081 reads about On 10/31/2014 12:30 PM, John May wrote: > As a matter of interest which particular diode is causing these symptoms? > > On 31 October 2014 15:18, Todd Micallef <tmicallef@gmail.com> wrote: >> Charlie, >> >> Calogic appears to sell directly, they may even send you a sample. I guess >> it wouldn't hurt to ask. >> >> Todd >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > >