Repair video: Uniden HR2510 10m amateur radio debug and repair

[w2aew]

This video walks through the debug and troubleshooting process I went through to diagnose and repair my friend's HR2510 10 meter amateur radio transceiver.  After being removed from storage, the unit would not transmit.  The problem turned out to be the failure of one component.

[Shock]

Another excellent video Alan.

[fpliuzzi]

Alan, I find both your 'live' and well documented repair reenactment videos, like this one, beneficial.

Thanks

[German_EE]

Transceivers like these seem to provoke considerable debate. Some will not touch them because of the CB connection but they provide a cheap way of getting on air. Have you done any transmit quality measurements because I am interested in using a rig like this to drive a 6m transverter?

[w2aew]

Transceivers like these seem to provoke considerable debate. Some will not touch them because of the CB connection but they provide a cheap way of getting on air. Have you done any transmit quality measurements because I am interested in using a rig like this to drive a 6m transverter?

I agree - these rigs are somewhat debatable.  I haven't looked at the transmit quality of it.  If the rig was going to be used by some hack, I wouldn't have repaired it.  In this case, I've known the owner for many years, and he's a long-time ham.  The only modification he's made to the rig is to add some circuitry to allow the mic up/dn buttons to adjust the VFO just like the front panel VFO knob.

[G0HZU]

Transceivers like these seem to provoke considerable debate. Some will not touch them because of the CB connection but they provide a cheap way of getting on air. Have you done any transmit quality measurements because I am interested in using a rig like this to drive a 6m transverter?

I've got a couple of them here somewhere. They are designed by Uniden which usually means two things.

1/ The build quality throughout is extremely good for an illegal 'export' CB radio.
2/ The RF performance is usually compromised in several areas. Often comically so.

Uniden did make some very good 40Channel AM/SSB CB radios in the 1970s for the USA market but they also cashed in on the illegal export market with 120channel (or more) radios. These were always badly designed in terms of how they expanded the radio beyond 40 channels.

The HR2510/Lincoln/2830 appeared about 25 years ago and the early ones were pretty awful with obvious design issues. My guess is that they rushed its development to cash in on a fading market. There are various 'mods' available to correct the flaws on the early ones.

But all of the versions have fairly dirty transmitters in terms of noise floor. However, this is really only going to bother any nearby hams or CBers who are trying to use 12m or 11m or 10m bands. The HR2510 transmits a broad spectrum of noise across all of these bands. This is much, much worse than a regular CB radio in this respect.

The early ones are also awful in terms of dynamic range on FM receive. One of the worst CBs I've ever seen in this respect.
They are also very easy to jam compared to other CBs. This is again due to poor design by Uniden.

There are lots of other niggly issues with them and to me they are just another example of a badly designed illegal export CB (but with a digital VFO).

However, many people think they are brilliant radios so the best thing to do is see if you like using the radio yourself. The high noise floor on Tx isn't an issue if you don't have any (very) local CB/Ham users that would otherwise suffer each time you key up.

[German_EE]

OK, thank you for the transmitter information, I think my credit card will stay in my wallet as I do not want to go on air with an unclean signal.

[G0HZU]

The noise is only an issue if you have anyone local. Here's an old plot of one of these radios on a decent oldschool spectrum analyser.

The analyser has an external 30dB attenuator so the CB is transmitting about 10W (40dBm) on FM here. The noise floor pedestal is about 5MHz wide and is typically -116dBm/Hz with the attenuator which means it is really 30dB higher than this at -86dBm/Hz.

In a 5kHz BW this will be 37dB higher so the radio is churning out about -50dBm in noise power on every 5kHz channel bandwidth (across 25 to 30MHz) when the radio is keyed up. This would be enough to be heard for a couple of miles from your station.

25 years ago this would have been a big deal on these bands in urban areas but today it's unlikely to be a problem at all as the bands are usually empty and the nearest local could be 10 miles away or more.

Note:
If you use the front panel power button to reduce the power 10dB to 1W the noise level doesn't go down 10dB. It stays at the same level because of the way the radio is designed.

The noise pedestal is not a limitation of my analyser. If I inject a clean signal from a sig gen or a decent CB radio the noise is much lower

[mcinque]

Thank you Alan!