Lafayette KT-200 Receiver (same as HE-10)
Frequency coverage is 550KHz to 31 Mhz in four bands. It is transformer operated and single conversion with an IF of 455 KHz. The bandspread is marked from 0 to 100. The main tuning dial has the international short wave bands highlighted but not the ham bands. The set has 9 tubes including a 6DB6 as RF amp, 6BE6 oscillator, 6BE6 mixer, two 6BD6 IF amplifiers, 6AV6 for BFO and ANL, 6AV6 for detector/ first audio, 6AR5 for audio output, and 5Y3GT rectifier. An octal socket is located on the rear panel for attaching a Q-multiplier. A review of the HE-10 can be found in the May 1961 issues of '73 Magazine.
The set's tuning dial is copied from the Hallicrafters S-38 . The S-38 dial was designed by famous industrial designer Raymond Loewy, with the main half moon tuning dial on the left and the bandspread on the right. The tuning dial design copy is where the similarity to the S-38 ends. The KT-200 / HE-10 is a much more capable receiver with its dual IF stages, a tuned RF amp stage, separate oscillator and mixer, transformer operation rather than AC-DC, S-meter, etc. The original kit price of $64.50 made it an affordable receiver and an excellent value for the money in the 1959 to 1963 era when compared to, for example, a Hallicrafters S-120 at a similar price.
This radio was in good cosmetic condition and was working when acquired. The S-meter control had been replaced by a former owner with one that was screwdriver adjustable only. I replaced the control and located a correct knob for it and the BFO control. The large tuning knobs are not original. The originals look like large versions of the lower knobs and mimic the style of the tuning knobs on the S-38. If you have spare original tuning knobs, let me know.
After the usual safety checks and slow power up, it was obvious that the bandswitch was somewhat intermittent, especially on the broadcast band. An application of deoxit solved that problem.
The set has a tendency to distort when the audio is turned up rather loud. At first I assumed this was due to the AVC not working properly, but the problem is limited to the audio section. I will do further tests. The audio is capable of 1.5 watts and should be able to handle loud audio with a properly matched external speaker. I suspect that the audio output transformer may have been replaced with one having an improper impedance match. The capacitor across the output transformer primary is also suspect.
This little receiver is quite sensitive with its tuned RF stage and dual IF stages. While listening to 80 meter SSB trasmissions with a proper antenna, the sensitivity needed to be reduced. The proper procedure for SSB on a set not designed for it (no product detector) is to reduce the RF Gain (in this case the IF Gain, which adjusts cathode bias on the two IF tubes) and maximize the volume control. At the absolute minimum IF gain setting, many of the SSB signals were still too loud and BFO injection was weak. Also the bandwidth is too great for comfortable SSB.
For listening to AM broadcast and to international short wave, this little radio does a superb job with a decent antenna. Since the ham bands are not even marked on the tuning dial, the design of the radio appears to have been purely for the SWL market. Flywheel assist for both the main tuning and bandspread make it a fun SWL band cruiser.
The Radio Manufacturing Engineers RME HF10-20 converter was the previous item on the bench.