Some of us Hams have an interest in all tube type vintage Transceivers or Twins (separates). Many different radios exist such as Drake TR-4 series, Heathkit SB-100/101/102 & HW-100/101, Swan 270/300/350/500/700, Collins KWM-2. The National includes the NCX-200, 500, NCX-5 and a few others, plus the Hallicrafters SR-150/160/500 and SR-400 Cyclone. This National NCX 5 MKII is a dual conversion receiver with 100 watts PEP output using a pair of common 6JB6 transmitting tubes. All tubes in the NCX-5 MKII are very common and for sale everywhere. New receiver tubes lasts at least 25,000 hours. The radio has a mechanical digital dial that is normally accurate to 1kHz. The receiver has an unusual dual RF receive amplifier. It is similar the National NC-183D design and normally used in high quality receivers in years past. This dual RF amp makes for a very sensitive receiver and does not fall off in performance on 10 meters. I compared the National receiver to a Kenwood TS-950SD and was surprised the National was a little more quiet and seems to hear as well as the Kenwood. I suspect a very weak signal on 10 meters would be better heard on the Kenwood, but I had not noticed that. Do note the National was complete aligned, has out of tolerance resistors replaced and all new electrolytic capacitors in the transceiver & power supply. It likely works as well as new from the factory. The receive audio is a little more clear vs the Kenwood, but the Kenwood is about as good as I ever heard from a solid-state radio. The filter in the National is 2.8kHz wide for pleasant receive quality. I believe the selectivity is 4.6kHz at -60dB. This a quite good, but new radios are about 2.4kHz and 3.8kHz at -60dB. However, the National 2.8kHz band pass sounds much better vs 2.4kHz. All order transceivers drift and this National drifts a few hundred Hz from a cold start. Most in a first few minutes. After about 15-20 minutes warm up, it stays on frequency for hours- no detectable drift on SSB noted. The transmit audio is reported as excellent. I use an Electro Voice model 630 microphone. It has the desirable few dB rise at 1000 to 3000 Hz. This National radio has a RIT control, many tube type vintage transceivers do not have RIT. What is missing on the National is a noise limiter and frequency calibrator. On SSB, the noise limiter is not needed at least at my location. The mechanical digital dial is accurate enough that you always know where you are basically at frequency wise on SSB. The separate NCX-A power supply is a very nice design. It uses chokes in the low and high voltage for low AC ripple output. That means no AC hum in the receiver audio. Replacing the electrolytic capacitors do not require higher than factory rated capacitors unlike most other vintage power supplies. The better vintage receivers use dual conversion on the receiver, but the IF image issue on single conversion radios is not an issue with 300 to 500kHz bands (except 10 meters). Some vintage tube receivers do not have a 'tight' pass band as some are 2.4khz with 4.8kHz at -60dB. And, some have very noisy receivers. However an outboard AD COM DNR speakers makes the noise issue go away. Recommendations IMO the NCX-5 is a premium transceiver and would compare well to the Drake TR-4CW RIT. These National NCX-5 sell for about $300-$350 in good condition with the power supply. The Drake TR4-CW RIT costs about $1000 and up. If you do not mind circuit cards vs hardwired, the best all tube Heathkit is the SB-101. The SB-101 has a superior accurate tracking VFO vs the SB-102. The HW-100 & 101 SSB band filter is not near as good as the SB series. A good condition SB-101 with the power supply is about $300 to $400. Another great transceiver is the Hallicrafters SR-400 Cyclone. It has a calibrator, ROT, a notch filter, CW filter and a frequency calibrator, They are reported to have a very quiet receiver and cost about $600 and higher with a power supply. The Swans have a noisier receiver and costs less money vs the radios stated above. You get what you pay for, but the fun factor is good on any vintage transceiver or Twins. As for the expensive Collins KWM-2, prices have dropped in the last year and now can be bought as low as $600 with a power supply. The KWM-2 is very bad with CW though. Once these old vintage transceivers are brought back to specification with new tubes, some resistors and all new electrolytic (and some paper type) capacitors, the simple circuits will likely outlast your new solid-state transceiver. This makes for a good back up transceiver. All the tube type radios require a high impedance microphone, so shop carefully.