no tx on vhf HT-750

[dbfd588]

What would cause no TX on a ht750. It powers on and recieves and acts like its transmitting but not getting any power out. Whats the problem with it? Is it easy to fix and what approximately do the parts (if any) cost?

[Jim2121]

could be a number of things. the best way to find out is with a wattmeter...see where your settings are in the rss? if you don't have a wattmeter? can you get hold of a frequency counter? I haven't had a 750 in my hands for a number of years. but I would start there.
post back with your results..before you start buying parts PS: does it receive ok? the antenna/antenna connection came to mind...

[Batwings21]

What adapter are you using to measure power?

[dbfd588]

Its not mine itas someone elses. They said it recieves fine. Just no power out.

[Batwings21]

Its important that when testing a ht750/1250 to use the adapter that comes with the public safety mic, as others just don't work right. If he's not actually measuring the power out, just saying it acts like it has no power out, maybe he's got the wrong antenna on the radio, they are also very particular about the antenna.

[dbfd588]

yea im hoping its something simple. he's got it for sale cheap so maybe if I get it I can find the problem. He's got a OEM vhf antenna on it so I dont think it would be that. I may check the antenna connector on the inside and see if its come loose. Ive had to solder 2 of those back together on 2 other differnt radios. If he is testing the recieve with another portable then ofcourse its gonna recieve it being that close.

[AEC]

The HT750 has two devices, and either the driver or main PA is out, and I think that number is: Q3501 on the schematic, but I am not sure.

If you can hear the transmitted signal on a service monitor, then the VCO and buffer are operational, it's the driver and/or the PA that is probably the culprit.

But don't think it's a simple fix, as both devices are under shields and it requires a rework station with heat focus heads to properly repair this.

Unlike the CP200s and PR400s, this PA is not simply soldered via pins and screwed the the board.

I hope the warranty is still in effect, and if so....send it off to depot and let Circle-M or Mexirola repair it(or actually swap it out).

Most Waris models are 2 years, but........