Asmax-1 AM Stereo

[Levi C]

I saw the Asmax-1 Am Stereo on Ebay for $ 269.00 is this transmitter any good?

[Bill DeFelice]

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Asmax-1 AM Stereo Transmitter Technical Review

[Levi C]

Hey Bill thanks for the review.How much is the antenna tuning unit.

[Bill DeFelice]

If you buy one from ActRadio (assuming they'd even sell you one) you're looking at approx $200 for their "Extended Range Kit" option for their Talking House transmitters. You can probably built your own tuning unit, especially since there's not a whole hell of a lot to it.

I did a Google Patent Search of the transmitter and on page 10 there is a diagram of the tuning unit with partial component values. If nothing else, between this and maybe some info out of an ARRL handbook you could probably muster up something that will work equally as good if not better than the stock TH external tuner.

[LibertyNT]

This is the AM Stereo Transmitter Ive been wanting to get for a while now.
although I could get about 2 SStrans For the Price of 1 of those.

[Bill DeFelice]

This is the AM Stereo Transmitter Ive been wanting to get for a while now.
although I could get about 2 SStrans For the Price of 1 of those.

There are tradeoffs both ways. While the SSTran has a nice built-in audio processor you need to assemble it yourself - some people just don't want to bother or fear they don't have the skills to troubleshoot things if a problem arises. Granted, the ASMAX-1 is higher priced, but it's fully assembled and tested. I enjoy running the unit and listening to it on any one of my Sony AM Stereo radios, especially my recently newly added AM Stereo boombox.

[Tom Wells]

This looks very tempting to me, as I have no backup xmtr, and now my homebrew AM  is sick in the driver/output stage.
Down to 5 % signal out. Gonna hafta do some ripping and poking, and I never made a proper schematic for it.
First real bug it's developed in 15 years.  Tube swaps made no dif. Next it's looking for loose cx and failed caps.
Oh well, if I built it, I can fix it.

I've heard differeing opinions on whether a CQUAM stereo signal will decode simply by high/low tuning of two radios.
I swear I used to think I heard a difference on WSM and the Grand Ole Opry this way years back, but don't know what mode they used.
I am interested because AM stereo has an added apparent loudness advantage of 3db somehow.
I once knew how to explain this, now I just take it for gospel.

[Bill DeFelice]

Tom, I think you may be thinking of the Kahn-Hazeltine system of AM Stereo where you could use two radios, one tuned slightly below and another tuned slightly above to hear the stereo. I did a demonstration of this when I engineered a local 1KW daytimer that was using the Kahn independent sideband (ISB) system.

The C-QUAM system is phase modulated and can not be decoded with the two-radio method of. The only current advantage is that some AM radios that have HD compatibility can have the ability to decode C-QUAM AM Stereo due to the similarities in chipsets. I don't recall the particular model(s) but I had seen it written up.

Tom, I think you should consider the transmitter on the merit of being able to operate in AM Stereo if you have a C-QUAM receiver that you fully enjoy it. It's a nice unit and I use mine often but if you don't have an AM Stereo radio or you're on a budget and want to keep some cash in your pocket you could always built an SSTran.

[Levi C]

How far could you hear it on a car radio.The price is now down to $215.00 on ebay

[Bill DeFelice]

Wow, that's much less than I paid for the unit I got, but of course that was a long time ago.

The thing you have to remember is that you have to match the antenna externally since there is no adjustments on the transmitter for tuning. I used the external tuning unit which is part of the "extended range kit" for the Talking House AM transmitter (I came across one on a deal). the coverage it pretty comparable to the Hamilton and Chez transmitter, although the AM stereo is a little shaky on the fringe of the reception area. I didn't spend a lot of time with an AM Stereo car radio, so I may have to revisit that for a review update.