Heathkit AR-3 communications receiver

I have been attracted to this radio ever since they first came out but I never actually bought one. I either did not have the money and then, later, did not need it because I had something much better.

Recently I traded a 4-125 tube for an AR-3 in as-is non-working condition.

When the radio arrived parcel post in a Mr. Coffee box I expected the worst but the damage was not too bad. The radio had been shipped loose in the box inserted loose in its wooden case. The case was broken and the metal mounting tab that secured the speaker was broken off the speaker frame.

No problem on the case. It was wood and a little glue and clamping got that back into like new condition. The speaker bracket was originally spot welded to the speaker frame. This had broken before and been repaired with epoxy, J B weld to be exact. Well it did not hold up to the shipping stress. Guess loose peanuts and a lose radio in a Mr. Coffee box was not the best way to treat this thing.

Instead of trying to glue the bracket back on, I decided to solder it. After thoroughly tinning both the frame and the bracket I was able to effect a good repair.

I had been warned that the radio did not have any knobs. After searching the junk box and other places I finally found enough knobs for the controls. Powered it up. Nothing. Dead radio except for the front panel lights. Turns out the 2.7k 2w resistor in the power supply filter section was open. It did not look open but it was discontinuous. Replaced it and and the audio section seemed to work okay but the radio still did not play.

The mixer did not work. The 12BE6 had B+ on the cathode as well as the plate. Found two problems. First, the antenna coil in the cathode of the mixer was open. No problem, a little heat and some solder fixed that. Second, the ground return of the mixer oscillator coil was going to B+ instead of going to ground. Noticed that the mixer tube socket was a molded plastic socket while all the rest of the sockets had been of the cheap fiber type. I suspected that the mixer socket had been replaced and mis-wired. Mixer worked fine after I soldered the ground return back to ground.

I do not regret not having this receiver as a novice. It is a minimal and clever design but no match for the Hallicrafters S-85 I ended up with as a novice.

The AR-3 is very good on the broadcast band. Not so great on the shortwave bands. It is better than a regen but a single 455khz IF amp with no RF amp preceding the mixer makes for low sensitivity and selectivity. The first audio amp doubles as the BFO for CW and SSB. That is a clever solution but stability is not good enough for easy and reliable use on SSB. It does okay on CW.

It could benefit from the addition of a Q-multiplier and the mixer plate is brought out to a phono jack for this purpose. Power for accessories like a Q-multiplier is brought out to an octal socket on the rear apron. Use of the mixer plate connection would be safer with the addition of a series capacitor to keep the B+ voltage off the phono jack.

Also, the primary of the transformer is not fused. The addition of a fuse and holder would add some safety.

It is doubtful that I will actually use this radio to do any hamming, but, paired with my old DX-35, the set will remind me of how things used to be.

Explore posts in the same categories: HamRadio

One Comment on “Heathkit AR-3 communications receiver”

  1. admin Says:

    About one month after this radio was brought back into service, the dial lights went out.

    Dial light replacement is always a PIA, but Heathkit went out of their way to devise a design for the ar3 that would make the task a truely memorable experience.

    Replacement required removing the cabinet.

    While I had the cabinet off I decided to tweak the calibration. Good decision. The calibration was WAY off! The radio is now not only reasonably ‘on frequency’ but also has become much more sensitive.

    Oh, and I replaced the series connected #47, 6vdc bulbs with lower current, parallel connected 12vdc bulbs. Mainly because I had no #47’s, but the 12vdc bulbs claim to have 5x the life of the #47’s. Hopefully I will never have to replace bulbs again.


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