A Look at the Worst HF Rigs Ever--And How Hams Revive Them

Everett smelled just about as bad. If i recall there was one in Bellingham too.
Kimberly clark left Everett i guess? Did Tacoma finally cave in?

 

I got hold of a Eico 753 rig cheep at my then local ham club. I did a complete check-over of the radio has per the manual and found a lot of mods that would have never worked. Or who ever had built it could not read the resister colour code. When I checked who had done the work. It was two guys who worked at Cardiff Uni. Obviously not Professors. I am Ex. Army and was a operator, not a Tech. But spent a lot of time in the Workshop discussing radio circuitry with the Tech sergeant. One of the corporal Techs there stuck his nose in and told me I was talking rubbish because I mentioned the design of a Tank circuit. In his ignorance he stated that there was no such thing as a "Tank circuit". He got told to shut up and learn by the Tech Sergeant. I bet the guy felt such a fool afterwards when I drew the output stage for a transmitter and pointed out where the "Tank circuit" was. I was fairly good at circuit diagrams. I had trained has a "Spec Op". on leaving "Boys service". We had to learn and know the circuit for The Racal RA 17 triple superet Rx. with the "Wadley loop" stabilizer. This was part of our trade test. I drew this as part of my ham exam where it asked for a typical receiver block diagram or a transmitter diagram. So I drew both and got a pass with that from The City & Guilds Board.

 

The worst radio I ever had was Tempo-1 that thing would drift 5kc an hour.

 

I had an HX-20 - was my first transmitter, as a novice in 1976. Gotta love all those big chrome knobs! The original builder had miswired it, so that the final grid bias (noticeable on CW) was fed somewhere else than into the tube. It must have smoked a resistor, because a 10-watter was installed where a 1/2 watt was supposed to be. Worse yet, on CW, the final plate would quickly turn red because the tube was not being cut off properly.
Once I found the wire harness mis-route problem, and moved the offending wire over 1 position to the correct terminal strip lug, all was well.
Found out also that the elaborate worm-gear train that drove the VFO tuning did not like grease - made things stiff and jerky. Replacing the grease with sewing machine oil resolved that issue.
Can’t imagine using that thing mobile, though - what a hand-full that would be (with a separate RX!)

 

Yes. A pi output network is a peaked low-pass filter, so one-tube-oscillator rigs with pi-net outputs should use only fundamental crystals and not crystals on subharmonics of the output. (And so every time I look again at that ARRL Handbook one-tube, pi-output-net Novice rig that got to 21 MHz with a 10.5-MHz crystal I wonder how many of its builders got extra mail from the FCC.)

A rig not mentioned here so far is the Knight T-60 -- a disaster from both the RF-design and RF-fluent-layout points of view. A cheapened clone of the Hallicrafters HT-40, it also suffers from the HT-40's "subharmonic output" problem whenever multiples of the crystal fundamental are used, as the driver-final coupling circuit is a barely-peakable low-pass pi network, meaning that neither the driver-final net nor the final's pi output net rejects the crystal fundamental to any significant degree. And the rig's unshielded (in the original release) oscillator-driver tube is just a few inches away from the solenoidal pi-net coil. And the front panel crystal socket is connected to the set's triode-crystal-oscillator grid by an unshielded wire that closely approaches driver and final circuitry and is nearly 9 inches long.

The most insidious T-60 flaw is that mentioned by George Grammer, W1DF, in his QST "Recent Equipment" view of the rig: The T-60's 6DQ6 final is not neutralized, and as a result operates largely as a locked oscillator. Grammer reported that especially on 80 meters, the rig's crystal oscillator stage had trouble achieving and maintaining control of the output frequency. (So, from the "Bug or Feature?" department, fast forward to a few-years-ago post by a correspondent in the Facebook "Novice Rig Roundup" group, who reported that his T-60 was the only rig that allowed him to use 40-meter crystals on 80!!)

But my fave sleazy T-60 economization has to do with how its designer(s) worked to limit the key-up HV-rail soaring that's so cheesy and scary in the HT-40. (In my stock HT-40, HV was 560 V key up and 430 V key down--a 130 V swing!) The T-60 hides the problem by hardwiring a 2.2-k resistor across the keying line so that the set's keyed tubes, especially the 6DQ6, are always conducting enough to pull down the HV during RECEIVE but not enough to turn on the crystal oscillator. Cue Frank Zappa's "Cheepnis"...

 

I once had a Realistic DX-302 receiver. It was horrible. I sent it in for service, and it didn't work
any different when I got it back. Two tin cans and a string worked better.

 

A bit short of 100% accuracy on a lot of your facts about those radios

 

I agree totally. Put a 753 together from the kit in 1967, with the solid state VFO, and it worked great for many years. VFO was pretty good to begin with, but there was a mod that I think involved replacing a couple of capacitors with npo types, and MAYBE moving a power resistor out of the VFO enclosure to reduce heat on the vfo circuit. Was rock solid after that. Good audio like you say, and using an Astatic D104 mic would punch through static very well. Drug it from one end of the state to the other, ran it mobile, hooked it to all manner of antennas and it just kept going. Can't say I miss it much, but it did good by me.

Steve
WA0ODF

 

My first rig was a very-much-converted WS19, a WW2 Canadian tank radio. It had a VHF section as well as HF, and in the only QSO I ever dared have on 2 metres it drifted right across the band from 144.0 to 148.0MHz in one over!

 

Eico 7 drifty 3!