Using HF rig as AM radio receiver

[jordan]

Is it true that an amateur HF rig could be the best AM radio receiver you could have?  If you put up an HF antenna, it would almost certainly be able to receive signals at MF frequencies, and the receiver is well-designed to receive weak signals.  If I move to around Knoxville, I know that there are many stations in east Tennessee that play bluegrass and Southern Gospel music, but most are on AM.  I figured an HF rig would be able to pull these in better than anything else.

[skeezix]

Not really, but it depends on the radio. They're great on the amateur bands and that's they're designed for. MW is for convenience and I've found that in general, coverage there is mediocre. Some radios are better than others at MW, but if you want a MW DX radio, don't look to the amateur HF transceivers.

I do have a few of them. The Yaesu FT-847 does a pretty decent job on MW, but my Kenwood TS-690S does a mediocre job. Since I also have a National NC-183D that sits near the TS-690S, the old timer is the one gets used for MW. And for general HF listening to SWBC, the NC-183D also gets used more than the TS-690S. Why? The audio is superior. When I need something more than what the NC-183D can do, say for blocking adjacent stations, knowing what exact freq its on, SSB, then I'll switch to another radio, whether that be an HF transceiver or SDR.

One other thing with the amateur transceivers, is some have narrow AM bandwidths (e.g. FT-840 without the extra filter) and that makes listening to any AM signal miserable, especially music. The FT-847 & FT-690S have very wide filters, so that is not a problem for those.

[BoomboxDX]

I've never used a ham transceiver, but I've been involved in the MW hobby for a long time and read a lot of reviews over the years, and aside from SDR's (which a lot of the high end MW DXers use now) the big rigs that seem to get the biggest thumbs up from MW DXers have been Drake R8's, and then maybe the Icom R75.

I don't know what radio you use now, but chances are high that it's fine for MW, just get an external loop to boost the signals a bit.

If you don't have one, or don't feel like building one, even the readily available Eton AM loop will do a decent job -- although I haven't used one of that particular brand, I have similar loops made by other manufacturers -- a Radio Shack loop and a Select-A-Tenna, and they both do the job really well.

[audiokaos]

It also depends on what you're after from it. Looking to pull in distant signals or good audio? I have an Icom PCR100 that was fairly deaf RF wise, but you could really open up the audio bandwidth & it sounds great. But if there are high power local adjacent stations, you'll want tight bandwidth. In the States I hear IBOC is also a huge challenge for MW dx'ers, so not sure what the best route for that issue is. I'd guess you'd be stuck with squeeky sound, but could be wrong.

[ka1iic]

The best Am receiver I ever owned for AM was a Hallicrafters SX-28 but those are a bit hard to find these days.

My Yaesu Ft817ND is pretty good on AM but not the greatest in wide band AM because of the limited bandwidth that is common on amateur receivers.  But considering the shortwave broadcasters these day wide band reception isn't all that important.

My question to you would be what do you want?  HiFi AM on shortwave these days is very rare indeed.  Most of the shortwave stations I have heard lately have very poor audio response to begin with.  And I say that about many of the 'commercial' stations here in the U.S.  WBCQ is about the best in audio quality and very few come even close to their audio.  One station I have heard often  (don't remember its call sign) has a very nasty parasitic on their audio and it is so bad that I can't stand listening to it even in a much narrower band width. That is just a case of bad engineering IMHO.

One thing about my FT817ND that bugs me is that trying to receive an AM station in the USB or LSB mode is that the sideband detectors are so good that this receiver tends to discriminate against AM signals altogether.  That is to say the SSB detectors are very good for what they are designed for but not for AM reception. That is a pain when I am trying to receive a weak AM signal in the SSB mode.

With the older receivers (like the SX-28) you could 'zero beat' the AM signal with the BFO and that would enhance the AM signal so you could copy it but with these newer SSB detectors it doesn't work well for me at all.

Most of the amateur radio receivers these days the AM mode (detector) tends to be nasty with a lot of distortion because of the detector design thank goodness the FT817ND isn't one of these, that was one of the reasons I picked this rig for my new station.

I hope I haven't confused the issue too much for you. If you need more info I will try to follow up later.
 

[Pigmeat]

There are a lot of Kenwood 440's on the used market. The receiver section is identical to the vaunted Kenwood 5000 tabletop hf receiver. The 440 normally sells used for between 250 and 450 bucks.

[audiokaos]

The best Am receiver I ever owned for AM was a Hallicrafters SX-28 but those are a bit hard to find these days.

Very true. Had a hallicrafters sw receiver as a kid & more recently a SX101. Tubes just love AM. Just finished restoring a Heathkit DX40 TX as well. Hope to get that on the air soon outside of just a dummy load.. Need crystals or gotta build a vfo first though...

[Jari Finland]

Is it true that an amateur HF rig could be the best AM radio receiver you could have?  If you put up an HF antenna, it would almost certainly be able to receive signals at MF frequencies, and the receiver is well-designed to receive weak signals.

Yes and no.

The communications receivers Yaesu, Icom and Kenwood did put on market during 70's-90's almost invariably had a MW attenuator to protect them from overloading. In places like Finland all those systems had to be removed and modified before one could use them for dxing. In simpliest case modification could have been to cut 1 wire inside the unit. In more complex case components had to be soldered out and new ones placed in.

Also 70's-80's communications receivers had very seldom real narrow IF filters. How they dare to call 2,7 kHz bandwith "narrow", is still beyond me. "Wider" selections might have been something like 4 kHz and 7 kHz, and at least one of these two was completely useless for all purposes. I would have wanted to see 2.1 (or 1.5), 2.7 and then maybe 4 kHz. The result: During period circa 1975-1995 many hundreds, maybe even a thousand dx receivers in Finland were opened, old filters were thrown away, and new ones placed in.

Unfortunately every modification more or less ruins the performance of receiver, because it was not designed to work like that in the first place.  

And now the shocker: Again, almost invariably those communications receivers were simply the receiving units of transceivers, packed alone in a different box.

This is why I wouldn't have high expectations if I had to use a nearly-vintage solid state transceiver.

On the other hand, the very last communications receiver Yaesu produced, FRG-100, was excellent and didn't suffer these problems. The reason was simple: it was designed as a communications receiver. Alas, around that time in 1990s demand of those receivers sunk, and it remains today as the last classic communications receiver Yaesu made. AOR-7030 and Lowe HF-225 are very recommendable too.

Then if you are interested in high class used professional receivers a la Racal, Plessey, Telefunken, Siemens, Rohde & Schwarz, Hagenuk, AEG, even RFT EKD-500 of East Germany, the prices vary between 700 - 5000 US dollars but usually quality and performance is top-notch even after all these decades.

[ka1iic]

I forgot to mention that the Hallicrafters SX-28 was used by the FCC as their 'high end' (in its time of course) monitoring receiver. There was one difference between the commercial unit and the FCC unit. The FCC unit did not have push pull audio output but on a single 6V6 in the audio stage and the commercial unit have 2 6V6GT's in the audio output.