19-09-2018, 05:31 PM
I am well aware of the 2 different requirements.
My comment about lack of attention for CO6/501 at transmitter sites was very much to do with de-staffing. The engineers on transmitter sites were highly skilled and I never intended to imply otherwise. I don't know if the CO6/501 was actually used at unattended sites but it was an obvious liability. Hence the need for the CO6/509.
It's interesting to note that the IBA kept their Pye built CO6/501s until the bitter end. There were certainly reports of poor 405 signals due to converter faults but I don't have any references to hand.
I have worked on both an ex-IBA CO6/501 and a CO6/509 and have documentation for both. I collected the CO6/509 one evening from Crystal Palace c1987 and took it to the Vintage Wireless Museum. I got it going (only PSU faults at the time) and looked after it for a few years. Then it was mainatained by Dave Grant until it was finally replaced by an Aurora a few years ago. The Museum's '501 was another matter. It had arrived c1985/6 and was a maintenance nightmare. We were very glad to have the '509. Both the '501 and '509 are now with Electrokinetica.
You may be aware that Malcolm Everiss restored a CO6/501 to fullworking order a few years ago. This was a considerable taak. As you said, availability of some unusual semiconductors such as the OC140 was a big problem.
My speculation about replacing the CO6/502 was related to the availability of the CO6/509, well before the ACE. While I haven't looked at the problem in any detail, the '509 ought to have the capability of doing 405 to 625 conversion with relatively minor modification. I think the main issue is that in its usual 625 to 405 role the interpolator comes before the time redistribution. For 405 to 625 on a similar basis the interpolator would normally come after the time redistribution. No such problem would exist with the ACE as the 2 functions are essentially combined.
Your reasoning is certainly plausible. If the CO6/502 was good enough, then it wasn't worth any significant engineering effort to modify the CO6/509 to replace it.
Do you know if the ACE used for 405 to 625 conversion was largely dedicated to the task or reconfigured as required?
My comment about lack of attention for CO6/501 at transmitter sites was very much to do with de-staffing. The engineers on transmitter sites were highly skilled and I never intended to imply otherwise. I don't know if the CO6/501 was actually used at unattended sites but it was an obvious liability. Hence the need for the CO6/509.
It's interesting to note that the IBA kept their Pye built CO6/501s until the bitter end. There were certainly reports of poor 405 signals due to converter faults but I don't have any references to hand.
I have worked on both an ex-IBA CO6/501 and a CO6/509 and have documentation for both. I collected the CO6/509 one evening from Crystal Palace c1987 and took it to the Vintage Wireless Museum. I got it going (only PSU faults at the time) and looked after it for a few years. Then it was mainatained by Dave Grant until it was finally replaced by an Aurora a few years ago. The Museum's '501 was another matter. It had arrived c1985/6 and was a maintenance nightmare. We were very glad to have the '509. Both the '501 and '509 are now with Electrokinetica.
You may be aware that Malcolm Everiss restored a CO6/501 to fullworking order a few years ago. This was a considerable taak. As you said, availability of some unusual semiconductors such as the OC140 was a big problem.
My speculation about replacing the CO6/502 was related to the availability of the CO6/509, well before the ACE. While I haven't looked at the problem in any detail, the '509 ought to have the capability of doing 405 to 625 conversion with relatively minor modification. I think the main issue is that in its usual 625 to 405 role the interpolator comes before the time redistribution. For 405 to 625 on a similar basis the interpolator would normally come after the time redistribution. No such problem would exist with the ACE as the 2 functions are essentially combined.
Your reasoning is certainly plausible. If the CO6/502 was good enough, then it wasn't worth any significant engineering effort to modify the CO6/509 to replace it.
Do you know if the ACE used for 405 to 625 conversion was largely dedicated to the task or reconfigured as required?
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
