The AM Forum

Hello,

Does anyone know if there are any SDR Pan-Adapters that will work with the Hallicrafters R-274 Receiver.

The reason I ask, I noticed an "IF" out port on the receiver.  I haven't looked yet in manual to see what frequency it uses.

With this being said .... that is if that is what it could be use for?  (Wishful thinking!)

Thanks!

Ken

The IF output of the R-274 is not where you would want to connect any type of panadapter. Panadapters (SDR or conventional) are connected before the IF strip. Since it's a double conversion receiver either the input side of the 6 MHz IF (before the input transformer) or the input side of the 455 KHz IF (before the input transformer) would be good choices. 6 MHz connection would be my first choice if double conversion is used on all band switch settings.

The IF output could be connected to the vertical input of a scope to monitor receive signals. Useful to some degree.

Many, including myself, have used a SoftRock 455khz if converter on the R390A IF output with good results. W2INR had one setup for quite some time using Power SDR software. I remember he needed to attenuate the IF output because it was over-driving the SDR card. I believe he left the bandwidth open at 16khz which limits the panadaptor accordingly. But for QSO purposes it was very effective in receiving a desired station.

Now if you're looking for a full band view Pete's suggestions are most likely the way to go.

So I should look for a SDR Hardware/Software that works for 6 mhz.  I am glad I had asked not knowing I couldn't use the IF port as you mentioned.

Thank you Pete.


I actually read something sometime ago about the 390A being used with a SDR Pan-adapter.  This is what intrigue me to this idea for the R-274.

I don't necessary need a full view Pan-adapter, but a few frequencies to the left and to the right would be enough.  But if I could get more without to much struggle, then sure more is good!

Thank you,

Ken


Thank you Fred.

I will have to search and ask around.  Maybe I will get lucky!

Ken

I have attached excerpts from the manual.  Yes, on the higher bands the IF does get converted up to 6 MHz but then it gets converted back down to 455 KHz.  Note the output from V15: it has an output frequency of 455 KHz and outputs to J2.  You can take any of the older panadapters that work off that frequency and use it. I just gave away such a panadapter to a friend.

The two pages I took from the manual support my comments.  Hope yours works better than mine.  Some bands do not work.  I'm getting a friend of mine to work on it maybe this year [fingers crossed]

GL Al

There's hope !!

J2 is at the output side of the IF chain. That's no place to connect a panadapter. You want the panadapter on the input side of the IF chain.
The tap off point for a signal to the panadapter could at the plate of the V3 mixer through some small capacitance (maybe 2 to 5 pf) and the signal fed to the panadpter through a short piece of coax.

Point taken: I just thought the thread was having to deal with two separate frequencies (455 KHz & 6 MHz).  My particular use of J2 was to provide a 455 KHz signal to a Sherwood SE-3, an entirely different requirement.  I'm thinking that a cathode follower tapping off an early stage (as you described) and providing ~50 ohm Z for panadaptor applications.

Al

I agree with Al,  you need a low impedance output to the panadaptor.  A small cap (2-5pfd) when connected to even a short piece a coax (say 4-5ft) doesn't work.  Way too much capacitance in the coax to end up with any level a usable signal.

Fred

Obviously, this was typically  how it was done back in the "good old days":
http://www.radioblvd.com/PanadapterSX28.htm
However, with these software related dongles or boards, one might have to be more creative to get enough signal from the receiver mixer into a panadapter whatever. A lot depends on how much input signal the panadapter whatever requires.

That depends on what the operator wants Pete. As I said, if you want a wide full band (panoramic, if you like) view then you are correct. Sampling before the IF filters is necessary.

But if, as with me, the desire is to enhance reception of desired signals using SDR advantages then J2 will be fine. As with my R390A the view will be limited by the IF filter selected. I usually keep it at 16 kHz BW.

Hello,

I'm listening to everyone.  You guys have way more knowledge then I!

 :) :) :) :)

Ken

Budley has really summed it up nicely.  Actually, if we are talking about the modern SDR panadapter that approach comes along with some additional goodies.  In that case, I'd run with J2 - being inclined to take the "easy road."

For the best wide band display, Pete' comments would be the way to go.  Short, easy approach, Ken, is to just use the J2 connection and enjoy the superior AM detection.  Later on, I would do some serious research on Pete's suggestion and pick off very early on - I favor a cathode follower with a coax switch: "WIDE"/ "NARROW" where you could chose between the two points, off the 1st mixer plate and J2 respectively.

So, Ken you can play with the whole of superior detection and yet still see adjacent frequencies.  Run with it with the J2 approach and do some serious research on the early pickoff point off the 1st mixer

Al

Looking at a chunk of the band on either side of where you're listening, or looking at a specific signal, is my preference. This way, any anomalies within the IF strip (alignment or component choices) do not come into play when viewing it on a screen. IF strips can be mis-aligned, purposely staggered tuned, or can generate multiple peaks or skewed waveforms depending on alignment and component choices. Even if you just want to view a particular signal in detail on the frequency you're listening too, looking at it before the IF chain, I believe, is a much better choice. But, hey, this is hobby radio, hang it wherever you want.

Here is a good example of using the 455 kHz IF output of an R-390A with sensational results measured by Jay, W1VD :

http://www.w1vd.com/R-390ASoftRockdetails.html

I am hearing both sides of the coin if you will.

Knowing there is a simple solution and perhaps a better solution over all is just great news no matter which way one would want to go.

After reading Jeffrey's Post and the link on the R-390A and learning that the volume controls and such may be operated via the software isn't necessary what I had in mind.  Although it sounds like a better choice to enhance the 390 and so forth. 

But I think it would steer me away from the Vintage feel of operating the R-274.  I still want to tune the knobs on the R-274 as one would had to do in the past.

I already have an Anan-100 SDR receiver that I do use it in conjunction with a Johnson Viking Transmitter.  And It does perform well in all aspect of having it joined with the Vintage Transmitter.  

I am trying to keep the Vintage feel of both the Transmitter and the Receiver but also having a Pan-adapter only I guess I should mention.

The idea of the Pan-adapter for me is so I can see the receiving station's signal, especially to see how wide their signal may be and also so I can see my transmit signal of course during my transmission.  It also allows me to see if my transmitter is on frequency.  At lease this is what I do when using the Anan SDR joined with the Viking Transmitter.  Its something that I have come accustom of doing and I would like to continue to do so but without the Anan attached.  Just a PC monitor so to speak for the Pan-adapter only with no mouse control.

This way I would be receiving from the R-274 only with no enhancements.  If the receiver is only as good as the receiver was met to be then so be it.  It is what it is!  To me this is what make it a Vintage receiver and the ability to have that vintage feel of yesterday!

Call me what you will, but that's me!

So maybe I should ask is there anyway to create just a pan-adapter?  

Pete, your link that you had shown is exactly what I would like to have, but just a little bit more enhanced for transmit and receive.  http://www.radioblvd.com/PanadapterSX28.htm
 (http://www.radioblvd.com/PanadapterSX28.htm)

Sorry for the Old Buzzard Transmission post!

Ken

Ya still get to twist the tuning knob and RF gain and bandswitch.... The SDR gives more control over what you hear. A lot more than the vintage radio can.
fred