The AM Forum

I just picked up a McKay Dymek DR-22C and it is working but I would like to find a manual (either electronic or printed) for it if available.  It sounds good on AM and has an interesting 70s HiFi look.

Good luck with that, Rodger.  I had a DR-33 (the one with the slew tuning) and could never find a manual for mine.  As I recall though someone had a few pages scanned from the manual posted somewhere for the DR-22.  Google it and hopefully it'll come up.

Mine had a forest of Collins mechanical filters and worked well enough, but the AGC was a bit funky.

JN,

I see that Pete has them so I will place an order when he gets back from Dayton.

The DR-22C is a bit simpler with just two filters (4 and 8 Khz.) but from the block diagrams on the web there are a lot of similarities between the 22 and more expensive 33.  I am not sure if I will keep it but it will get a thorough audition.

Rodger

You'll never go wrong with a manual from Pete.

Let us know what you think.  I wasn't impressed enough to keep mine, although it wasn't at all bad.

There's a product review of the DR-33C with dynamic range numbers and spectrum anaylzer display of the relatively noisy VCO in the September 1979 issue of QST ... if you have a copy or access to the archives.

John,

I think the DR-22C was probably a very good broadcast receiver back when there was a lot on the shortwave bands.  The switch type tuning is perfect for tuning in an international broadcaster based upon a published schedule but it certainly isn't a band cruiser.  Although it does have a product detector tuning in SSB via 5 Khz. steps with fine tuning in between would be very awkward.  Its main claim to fame is low distortion AM detection.

Jay,

Thanks and I have QST on CD-ROM and I will look up the review.  I believe all of the early synthesized rigs had a lot of phase noise so I am sure this one is no exception.  For AM operation on the MW and SW broadcast frequencies it will likely not be bothersome.

The only problem I found with this one was intermittent loss of sensitivity which I traced to a RF choke with a poor solder connection.  The lead was flush with the trace and was never soldered properly, heating the connection and pushing a bit more of the lead through cured that problem.  This is one of the places where a
"calibrated finger" was the proper test equipment since it required a very light touch to narrow down this mechanical intermittent to a board and finally a component.

It does have very good AM audio but it is much more suitable for broadcast rather than amateur use.  It is unusual enough I will hang on to it at least for awhile.

The DR-22C tuned to the last local non-talk radio.

The AM detector in that thing is certainly memorable.  I was never able to scarf up a schematic so I don't know how they do it, but it does sound nice on AM.

Won't be leaving Dayton till Monday morning.
I have both the DR-22 and the DR-33. I've had documentation on both of them for at least 10 years or more. The DR-22 also has one less decimal position knob (they sub a +/- 5 KHz tuning knob)  then the DR-33. From what I remember, the schematic is spread over 9 to 11 Figure pages.

Crap, I shoulda asked you... a google of a DR-33 manual came up with no hits back when I got it.

In the meantime you can find the specifications of the DR 22C and on some other McKay Dymek receivers here:

http://www.radiopharos.it/Carta%20Scansionata-Scanned%20Paper/DR%2022C.jpg

and here:

http://www.radiopharos.it/Carta%20Scansionata-Scanned%20Paper/Carta%20Scan.%20Paper%20Index.htm

The downside to these type of receivers is that it takes four or five knobs just to tune the receiver. One of the power supply IC's has been discontinued with no plug-in replacement. I believe the binary switches for these receivers are unique to these models.