It is important to note that there is no definitive tube tester, neither analog nor digital, they all give only indicative results. What tube testers are really good at is taking snapshots of performance and comparing between tubes of the same type, that alone makes it worth having one. Any model from the TV-7 series will be a good candidate for that purpose.

In order to avoid confusions about the panel looks like, here is a special description:

• The FILAMENTS, GRID, PLATE, SCREEN, CATHODE, SUPPRESSOR switches are not voltage distributors, are connection distributors.
• The voltage distributors are the BIAS control and the FILAMENT VOLTAGE switch.
• SHUNT is a control that is required only when the FUNCTION SWITCH is on the RANGES A position, and adapts the maximum deflection of the meter to the characteristics of the tube tested (diodes and rectifiers).
• The FUNCTION switch selects TYPE of test or LEVEL of test.
• The PUSHBUTTON selected starts the corresponding test.
• LINE ADJUST is a control that adapts the input line voltage to the set and determines the internal voltages. This control seems marginal but is very important.
• The LINE TEST mark on the meter associated to the adjust of the LINE ADJUST control should reflect the internal voltages are correct when LINE ADJ pushbutton is depressed. Otherwise the tester may be "optimistic" or "pessimistic".
• The PLATE voltage applied to an amplifier tube is in most cases a fixed voltage of about 150 VDC, but may be substituted by 56 VDC on low voltage tubes holding down DIODE before depressing the MUT COND pushbutton.
• The SCREEN voltages are 130 VDC or 56 VDC, depending on tube characteristics, and using the above same procedure for applying 56 VDC.

About appearances and models:

• It must be remembered that what works on a device is not the appearance but the content. Given certain limitations and issues of the TV-7 (some of which are described on these pages), it is interesting to note that a TV-7 often outperforms in price other, more efficient tube testers. This is probably due to the fact that the 'MIL look' of a TV-7 is impressive, not to the fact that it is better than the others.
• There are several TV-7 models, IMHO no need to obsess over model D. This model is only very useful for people who dare to adjust the device (precisely the intention of these pages is to provide info to help easily on that) since all the main adjustments are readily available. Model B also has all the adjustments available, there is an adjust that is only in model D, but model B doesn't need it (R139, bias to range F). Model D is the only one that has range F, but that range is useless since there are no tubes that test ONLY on that range, and those that ALSO test on that range are VERY FEW. Test'n adjust procedures shown here also apply to model B.
• Something that points in favor of the model D is that it has ferrite beads in almost all sockets to safely test high transconductance tubes like VHF/UHF TV converter tubes (e.g. 6DJ8-ECC88). It is unclear if they are absolutely necessary on a well-wired and operated TV-7, since the Gm test frequency is very low (50/60 cs). And it is also doubtful that these ferrite beads will make up the difference in price with model B (which BTW, also has ferrite beads on leads to pin 5 of UX6 and pin 2 of UX7)... let alone a standard TV-7.
• The high price of the model D is not due to its scarcity, as strangely enough it is the most abundant model. IMO it is due to the perception that the latest is the best. Simply saying that the differences between TV-7 models are few, and none to make a clear difference worth a notable price increase.