The AM Forum

 Hello all,
    I have several receivers in my shack to choose from but most are currently "condition unknown". There is the Heathkit HR-10 and the external VFO which works well but seems to be a bit hard to tune.(havent tried it with the HG-10). I also have a pair of knight receivers (condition unknown) and a Hammerlund HQ-100c (condition unknown). I really like the SP-400SX but it might be a little bit over my level of expertise to get running and is probably going to be the most expensive to bring back to life. I need to do a full rebuild on the power supply, replace the caps in the reciever, and go from there. but one day i will have that one running. I would put the HQ-100c in the second spot on the list with the knight receiver in third with the little heathkit as my temp unit until i get another one up and running.
    Any thoughts on my list order and thinking? am i missing something that i might need to know? I am a newbie to AM and electronics repair but I am getting there..For those of you with real world experience with these receivers I would love to hear your thoughts

73 Matt WA4NLW

I had an SP-400 and I'm sorry that I sold it. I had an HR-10 and I'm not sorry that I sold it.

I agree with your rankings.

Matt,
I would focus on getting the Super Pro up and running, and look for working R-390A in the meantime. Look at auctionzip, heck I picked up a working Collins 32V for 5 dollars a few years back at a household auction, had it on the air the next day. It only needed knobs and a few tubes.
Ed - N3LHB       

I agree about re-habing the old super pro, but I don't think I'd look too hard for a 390.   They were a technical marvel for the day, but absolutely NOT a band cruiser.   They have the "feel" not unlike driving a tank. 

I'd recommend looking for an HQ-170, straight SX-101 and not the "A" if you want to work 160, NC-300/303 or 75A-3.  With a good tune-up, they are all very good daily drivers, and a lot more "user friendly".   

I agree with Mike on locating a -390 of any ilk. It's one of the best receivers out there for many reasons like weak signal work and stability. Tuning ease and AM Hi-Fidelity are not among those reasons. Both are fairly important to enjoyable AM operating.

You will never regret rehabbing and using your Super Pro. It has perhaps the best audio out of a stock receiver thanks to the P-P audio output and variable bandwidth adjustment. They get a bum wrap for drifting but this is based on folks who either got piss-beat surplus examples or who ignore the manual instructions about warm up time. Hammarlund did offer a modification to help stabilize the receiver sooner than prescribed in the manual, the post-war 400 may already have that improvement. If not, it can be found in the Receivers section of the handbook here on 'fone, submitted by W3GL.

Take your time going through it and be sure the check the IF cans as there are caps hidden inside (B+ too, IIRC). W3JN can offer you some excellent pointers on this line of receivers.

In the meantime you can use any of the receivers listed by Mike or find others like the NC-240D, SX-28, etc etc. The only issue with any receiver will be finding one that doesn't need the same overhaul your SP-400 does. The last thing you want is to use a bad receiver - design or condition-wise - that annoys you.

Look for an R-388/51J Collins receiver at a hamfest or locally... very excellent receiver for AM and
they are very much usually working, or need not much help.

One can find 75A-1,2,3 (not 75A-4, usually) also on the cheap at some hamfests.
These are fairly easy to work on, as things go.

Another option, until you get a nice tube radio running is one of those SDR Play or
similar SDR receivers. Later you can take the IF out, and stick the SDR Play on
the IF frequency, and get the benefits of the "magic" SDR selectivity and features
like synchronous detetor, etc...

The SP-400 is nice, but I'd say that owning an SP-200 and SP-600 I'd rather use the R-388
on a daily basis (which I have done for many years, until recently).

                 Ymmv.

      _-_-bear

Mike, sorry to disagree with you on this.

A well lubed and set up R-390A tuning is smooth as silk.
IF you have not had your hands on one that has been done properly, you've
missed a real treat!

The heavy, hard to tune examples probably have never been cleaned and re-lubed
with the proper lubricants. Also there are some that have been (dropped) mechanically
damaged.

They do vary a bit, just like things like guitars... :D

Interesting options here. This is all about preferences, and run what you got stuff. The HQ-100 might be a good receiver to start with while working on the SP400.

I have two stations where I run a Gonset G76, and a central Electronics 20A. I use two receivers that are not the same vintage as the transmitters. The G76 Receiver is so bad, that I use Tx only, and mate this with a Flex 5000 SDR in receive mode only. For the 20A, I mate that with an Icom R8500.

My feelings are that I need a better receiver that has superior filtering, noise reduction, frequency accuracy, and stability than what any of my BA receivers can do. Just my opinion.

I do want to eventually try my Mosley CM1 with the 20A, but other than a neat receiver, it offers none of the specifications that I really need.

Jim
Wd5JKO

Jim, I have experienced the same scenario, and wholly agree.  During the last AM Rally, I used a 75A3, 75A4, 51J4, and the SDRPlay RSP-2.  With the terrible noise level here, the RSP-2 pulled the AM voices out of the mud, where voice was not even discernible with the Collins receivers at the same time!  The noise reduction and the synchronous detection of the SDR is really amazing.  But I hope that at time in the future, the noise level will be low enough to enjoy the classic receivers.

I also have an Icom R8500, and have listened quite a bit, but have not paired it with any transmitter as yet.  I wonder if you have extracted audio and piped it to an external amplifier, without significant mods to the R8500?  I hope some of this information might also be of value to Matt as he formulates his receiver plans.

Thank you fellas so much for your thoughts and replies. I am soaking up as much of it as possible even though some of it is still a bit deep for me.

Matt WA4NLW

I thought that this was the default Receiver after the EMP!

No, never the '38. you need the Hallicrafters S-20R Sky Champion, sayeth Irb.


klc