AM Radio discussion. Directional arrays are FUN!
I am trying to figure out what divider ICs were used in the MF version of the Collins 310W-1 exciter (used in the 820E-1 and 820F-1 transmitters). The part number is crossed out in the manual copy that I have access to, which is actually for the HF version which does not use the divider ICs. The part looks like SC2239 but is hard to make out because of the heavy line through the part number. From the print they appear to be individual type D flip-flops in 8-lead TO-5 cans. In the exciter in my care they were replaced with a circuit built around a 7474 dual-D flip-flop - the whole circuit, including wire and perf board, was made from parts bought at Radio Shack, perhaps in the late '70s. Using the Q and Not-Q outputs of the second flip-flop to directly feed the bases of the driver transistors in the exciter was a poor choice. The load is not one that conventional TTL is happy with, the exciter output level could never have been as high as the original design (although it worked passably for many years) and it eventually damaged the 7474. I replaced the chip and added .01 uf capacitors to DC-isolate the 7474 outputs from the driver transistors and reduce loading on those outputs. The exciter now exceeds the factory spec for nominal output power and the 820E-1 is very happy.
Did you ever get a chance to look for the 310W-1 exciter manual? I am still trying to figure out what flip flops were originally used. No part number is given on the bed-sheet schematic, and although they look like possibly S-R flip flops I cannot find any flip flops in 8-pin cans with pin-outs that match the bed-sheet.
Hmmm... I can't get an applicable hit on that part number online, and can't find it in any of my databooks. The chips should be Z1 and Z2 in the exciter parts list.
I do not think they are RTL ICs because the crossed-out Z1 voltages in the HF version of the 310W-1 manual are way too high for RTL. All of the RTL that I have seen uses a supply voltage of 3.6 volts.
The schematic symbol on the bedsheet shows that they are flip-flops, but the labeling of the signal pins is unusual. I would think them close cousins to SR flip-flops, but the inputs are labeled "S" (set?), "C" (clear?), and "T" (timing?) instead of the SR labeling of "S" (set), "R" (reset) and "C" (clock). Also, the outputs are labeled "0" and "1" instead of "Q" and "not Q."
This was a type of logic certainly in use by 1965, as the 310W-1 was in Collins Catalog 43 (my copy dated 01-Jan-1966 by the original owner), and first used in the 820E-1/F-1 transmitters (it was also used in the 820D-1 when it later supplanted the 20V-3). It is almost certainly an SSI IC.
If the SN1147 part number is correct I would think it likely a TI chip, but as noted upstream the HF version of the 310W-1 manual parts list shows Z1 and Z2 crossed out as what appears to be SC2239, a Motorola device (which I also cannot find online or in my databooks). I would think it likely a DTL variant, but a family that I am not familiar with.
The reason why I would like to have a scan of the complete MF version of the 310W-1 manual is to have information such as the circuit description, which is replaced by typescript in the HF version of the manual.
We have an 310w-1 exciter. My manual also indicates a SN1147 for z1 and z2. I will look and see if by chance we have any on the shelf. Also will check my old cross reference guides. You might try seeing if you can find a cross reference to for SN1147.
Been there, done that, including digging out old printed ECG and SK cross refs, but I don't have any older than the mid-'80s - the device would have been a couple of decades old (and likely nearly that long out of production) at that point.
Thanks, but been there, done that. That datasheet is for a step-down switching regulator.
No luck finding any spares here for sn1147. Also looked thru my old digital logic books for the SN1147.Struck out. I am attaching a copy of the 310W instructions manual which has circuit descriptions if it helps. I think you are right that it some kind of jk flip flop. Problem is the 28 volt supply. My thought would be to create the flip circuit with a 7474 chip. Adding a voltage divider circuit to convert the 28 volts to 5 volts for the 7474.
- (2.26 MiB) Downloaded 24 times
Thanks for the scan - it is good to have a copy of the manual for the MF exciter, as all I has was the manual for the HF exciter plus the MF print as part of the bedsheet print. I will give the station a copy.
If you look at the voltage table on p. 4 of the manual VCC [pin 8] is 28.0 volts and VEE [pin 4] is 18.0 volts, so the chips are operating from a 6 volt supply.
Someone else made that conversion many years ago, with a 5 volt zener to regulate the voltage for the 7474. Problem was, they direct coupled the outputs, and that eventually damaged the 7474. I replaced it and added capacitive coupling.