Pro-26 motorboat noise only

[DeDawg]

Have a 90's vintage Pro-26 been sitting in a drawer for a few years. Batteries removed.

Wanted to listen to Mil Air without dealing with my newer "dynamic memory" scanners.

Pop in batteries, only get a rapid popping noise. No audio, popping does not vary with volume setting. Radio memories dead, but it accepts new programming. Just no audio.

Is this thing bricked from non-use?

 

[KK4JUG]

Isn't the Pro-26 a crystal scanner? If that's the case, you're probably going to need crystals. Don't hold your breath. Your chances are better at winning the lottery.

 

[wtp]

continuous coverage

• Frequency range of 25Mhz-1.3Ghz

less cellular.

 

[doctordialtone]

Pro-26

https://wiki.radioreference.com/index.php/Pro-26

"An earlier Pro-26 (Cat No 20-107) was a four channel handheld crystal model, and was sold from 1987-1989. "

 

[KK4JUG]

Okay. I was right but I was wrong.

 

[tvengr]

Motorboating is usually caused by bad batteries with high internal resistance or a bad decoupling capacitor across the batteries. Discharged batteries can cause it also. Did you try an AC adapter?

 

[DeDawg]

Motorboating is usually caused by bad batteries with high internal resistance or a bad decoupling capacitor across the batteries. Discharged batteries can cause it also. Did you try an AC adapter?

Going to see if i have one in my junk box. Looks like it takes 9V negative center pin from the graphic on the back of the case.

Stuck in fresh AA batts to check if the Li-ions were dead, same same.

 

[DeDawg]

Found a plug that fit and fired it up on a power supply. Motorboating is just a lot faster.

No batteries installed for power supply test.

Weird, the radio was working fine when I put it away. a couple years ago.

 

[wtp]

9V center negative. yes.

 

[tvengr]

From what I read, the Pro-26 has a memory retention capacitor. After a few years, I would expect the capacitor to be discharged and the memory cleared. The fact that it accepts new frequencies would indicate that the microprocessor is working. Try entering your local VHF weather frequency and see if you hear anything. If not, back off all the way with squelch and see if you hear noise.

 

[DeDawg]

Edit: Well, belay what follows, after turning the 26 on several times this morning, it is back to motorboating. I think I can barely make out the voice on 162.40 WX. Can hear open squelch, but not loud.

On the basis of what I encounter on a base radio (Ribbon cable connection) that periodically has issues, I took the 26 apart to look for corrosion or anything. No ribbon cables, but header connection between boards. Mated and de-mated these several times to clean up the contacts.

Put it back together with fully charged batteries and the darn thing works now. Or not, after switing it on and off.

 

[tvengr]

If that scanner has a volume control with an on/off switch, try spraying contact cleaner into the control. If switch contacts have a high resistance, it would be the equivalent of a poorly regulated power supply and could cause the receiver to break into oscillation (motorboating). It would be the same as the problem caused by bad batteries. The fact that turning it on and off causes intermittent problems indicates that could be a possibility.

 

[DeDawg]

Good call on the on-off switch. might explain why the issue comes and goes, showing up after a few years of no operation. Seems to be stable now, but the old radio has the infamous Pro-26 low audio problem, so not sure I want to open it up yet again.