My First HD Radio

I have been looking in to getting an HD radio since I first heard found out about them a few months ago... yes I know they have been out longer than that, I just did not pay attention.

However it seems I missed the boat and all the inexpensive HD radios have been sold and there aren't many out there of decent quality and of reasonable price.

I was tipped off to an ebay auction for a Directed dmhd1000i hd radio for $25 bin "free" shipping. Not including shipping the unit cost me $11.

I just got it today. It was NIB and looks like it was never opened. It was also marked "Not for Resale".

This is not a standard table top radio. it is meant as an add on to a car stereo.

Here is what came in the box:
The radio unit.
Control panel with about 10 feet of cable.
a remote.
2 antenna adapters.
mounting brackets.
and a billion miles of wire to hook it in to power.

To test it I threw it on my bench and hooked it up to a 12 volt power supply. although it has an interesting way that it has to power up.

There are 3 wires Yellow, Red, and Black. You hookup the Yellow to a constant power source, the black to ground and the red to a power source that is switched.

To get it to power on I hooked it up with black to minus, yellow to positive, and then used an alligator clip to connect red to positive after the yellow was connected. If you do not do it this way the unit will not power up from the display.

Audio output is rather low but way more than strong enough for my homemade amplifier that has a 12ax7 input and single ended 35c5's for output. I have to turn the volume way down for comfortable listening. There are no specs on what it's audio output is.

There are 2 modes of audio out, one is through stereo RCA connectors and the other is through RF modulation through the antenna output to any frequency in the FM band. I have not tried the latter.

The unit is currently connected to a Discone antenna above my roof line.

FM analog sensitivity is excellent, I can pickup kcdx a 2700 watt xmitter 67 miles away (not HD) with a reasonably good signal. kvit a 10 watt station about 12 miles from me that is understandable (not HD).

FM HD reception is excellent for ALL stations in my area that have it. The unit takes about 7 seconds when tuned to an analog station to lock in the HD signal. Once locked in, the transition to HD is noticeable as the music quality improves, the noise floor almost disappears, and the volume drops slightly.

As for AM Analog sensitivity is excellent, kazg comes in great using either my discone or my 67' random wire antenna kazg is a 5000 watt daytime and 50 watt night time station. After sundown it still came in great and is 4 miles away from me. Most of my AM radios can barely get this station after dark.

There are only 3 AM HD radio stations in my area (that I could find). 2 are talk and 1 is a religious music station. 550 would not lock in after sundown even though it did earlier. The religious station locked in but sounded terrible. I think this is because of the recording quality of whatever they are transmitting since it sounded terrible in analog. The other talk radio station on 910 comes in very clear on HD or analog. Time to lock in seemed to vary for AM stations but was about 7 to 15 seconds. AM HD lock on was similar to FM with static and noise all but gone and sound quality improved.

On the underside of the daughter board with the large chip on it, there are several tiny LEDs that blink rapidly at a regular rate.

When I first powered the unit on the audio sounded not very good with what I would describe as clipping or static, but that has since disappeared, and all stations sound fine. I have not noticed any compression artifacts in any of the Digital streams. After about 2 hours use the unit is rather warm, about 115° or so.

My plan is to mount the DMHD-1000 either in a box or somewhere near my Silvertone 7407, with the control panel mounted somewhere that I can see it, and use the remote to control it.

I found that these suffer with a problem on the RCA connectors of over modulation.

There are 2 fixes for it, 1 I have confirmed works and the other I have not tried.

The first is to use the FM modulation mode, I have not tested this. The other which I can confirm works is to connect the ground tabs of the RCA connection to the metal case, and on to ground. This is the only problem I have found with my unit. Once I grounded the RCA shields the audio signal cleared up completely.