12-07-2015, 10:19 AM
They have even fitted rivets in the component holes to stop dry joints. That indicates even more that it is from a mobile set.
|
A Tiny Pye Amplifier
|
|
12-07-2015, 11:12 AM
The same item? Not a lot more clue wise but if it's the same item it has an NSN number:
https://www.nsncenter.com/PARTNUMBER/AT27542# Maybe Email the Pye museum? Lawrence.
12-07-2015, 11:19 AM
Looking at the -ve end of C6, I can see why Ref saw rivets. Obviously, you have it in your hands, but from the pictures, I'd have said rivets too. Either way, it seems extravagant at a glance, especially as the layout doesn't appear to use tracks on the component side, but then many of the other PCBs in the PMR gear linked earlier are double-sided, so it's no hassle. Mind you, I remember Philips using rivets instead of PTH in their (very expensive!) CD players in the mid '80s. And a major source of trouble they were, too
 I've got a lot of those square ceramic jobs, though mine are mostly yellow. The largest value I have is 22n, and it's sensibly labelled "22n" rather than 223 or similar. They do go up to higher values IIRC. 7n5 gives a -3dB point of 125Hz if 750k is assumed for IC1. Or 96Hz if IC is o/c. Closer to your measurements, I suppose, and for comms purposes, going any lower would be a bit pointless. Interestingly, C6 has its pole at 16Hz when working into 15 ohms, so I wonder why they didn't save a few pennies and reduce it to 100u (106Hz) or 150u (70Hz) or even 220u (48Hz)? Either way, easy to increase C1 if needed in whatever application you put this to. Those Ferrograph test sets were lovely. Manually-tuned notch filter, as was common then, but capable of decent depth. That's a fascinating picture, Lawrence - do please tell more
12-07-2015, 12:08 PM
I guess if you're churning out the rest of the PCBs as DS PTH then you just carry on - why change?
I've actually replaced C6 with a 470u so I've done the job for them  In reality I expect it was more a matter of whas was in the Stores. Alan
13-07-2015, 08:05 PM
OK, last Lap.
I hooked it up to one of my Maxim 2s - 8R Impedance - and af from the Headphone Socket on my RA-17. I don't posses an iPod, Pad, Pid, Pud or any such and getting out a Record Player seemed OTT. And it works very well apart from the limitations of the Source. Pushing up the I/P to the point of clipping on the Peaks produces enough Volume for anyone apart from the Lunatics with the big Amps in the back of their Cars. So, back to the real world - 450v on the HT Rail and a nice glow from the Heaters Alan |
| Users browsing this thread: |
| 1 Guest(s) |