Often, I will write up my progress on projects not as much for your benefit but because the process of writing things down helps to organize my thought and then there is always the option that others who are more knowledgeable can respond and tell me everything I am doing wrong.

The Harris RF-5022, amplifier and auto tuner were supposed to be a simple project, quick flip to try to build up some money for the Hamvention next month, but like most things in life things don’t always go as planned.

Little background on the radio, it was owned by a DoD contractor and ended up belonging to me after a long and drawn out process. The radio sat in storage for at least five years, maybe more. Now I have it. First problem after getting it was building up the ten-pin cable between the R/T and the amplifier. All the other cables came with the radio including a ton of documentation.

Built up a cable and then discovered that without the password the radio was locked on 1.6 MHz Once the password problem was resolved thanks to help from this groups had a couple days of operation changing frequency, mode and running all the self-test without issue other than the memory batteries being dead I turned the radio off and when turning it back on it locked up. Nothing on the display and no effect from the controls.

New problem, the radio just sits there like a rock!

Ok, more documentation more testing. First let me tell you what I think is going on in the radio. The 5000 family’s control card (A6) is built around an 83C51, MAX695 and some SRAM that controls the other cards like the synthesizer (A1), receiver- exciter(A2), interface (A8) along with the ALE and Modem junk via a high-speed data bus. All communications with the outside world are thru a couple RS-232 ports from the interface card (A8) that support the control head (A20) and the remote-control port on the back of the radio.

There is also a power supply- time base (A7) that’s on the high-speed bus too. The control head (A20 and friends) has its own 83C51, MAX695 and SRAM and is a terminal for communications with the A6 card along with providing analog audio to and from the radio.

Where things stand, or at least where I think they stand.

I can turn the radio on and all the power supplies +15, -15 and 5 volts come up. The synthesizer comes to life and locks the radio to 1.6 MHz the receiver will receive SSB on that frequency so I am going to assume that the CPU and high-speed data bus is up and running. During this entire process the control head lights up but has no display and no controls have any effect, except for the volume control and that’s analog so it doesn’t count.

My speculation is that the CPU in the control head is not running. I did remove the battery in the head and that makes no difference. Starting to think the next step may be to build up a serial cable for the back of the radio and see if I can get anything to happen from that port?  Another option would be to build up a ten pin cable so I can operate the head separated from the radio and that will at least give me access to get into the head and see what’s going on.

My other thought is that the control card (A6) may be locked up or may be forced into reset by something like a bad power status or something from the MAX695, maybe its holding the CPU in Reset? I am on the verge of sacrificing the ALE card to build a 30 pin extender so I can see what’s going on with the controller card.

Would be curious to hear what others have to say about the synthesizer and other cards and if they have ability to come up repeatedly on channel without information from the high-speed data bus?

I am leaning more towards the idea the control head is at fault and think trying the external data port would be a good test, but then the question is do you need the control head to tell the control card to activate the remote port and do things like set baud rates and the like?

Just writing this it occurs to me that I can monitor the traffic to and from the control head and that may reveal something? There you go, did not think about monitoring the RS-232 bus between the radio and the head before this and now can’t wait to set it up and try it.

Ray F/KA3EKH