Vinnie;

The answer is "it depends".

If the alignment procedure requires you to measure voltages and adjust for
specific values then the scope and the probe must have a bandwidth beyond
the max frequency of interest. For example at 27 MHz the scope and probe
have to be rated for more than 30 MHz. Most bandwidth specifications are at
the "3 db" points meaning the response is down by 50% at the stated
bandwidth. Depending on the filter used on the scope input channel the scope
response may roll off at 3 db per octave, doubling in frequency, or faster.
Of course the response starts to roll of somewhat before that point.

Now if all you're looking for is a relative reading, peak response or
modulation checks for example, a lower bandwidth scope and probe could work
so long as the response is enough to give a good display on the screen. I
would guess a 15MHz bandwidth scope may work OK.

One other thing to watch out for is circuit loading due to the scope probe
resistance AND capacitance. The probe capacitance can be in the order of
some 10's of picofards. This can cause serious circuit detuning if you use a
probe in a circuit where the tuning capacitance is in the same range as the
probe to as much as 10 to 20 times that value.

I've seen a lot of very nice 30 to 100 MHz scopes for sale at various
hamfests for very reasonable prices. If you don't have one and you plan on
doing more electronics work investing in a good scope is a good investment.

--
Regards,
Leland C. Scott
KC8LDO


"Vinnie S." wrote in message
news
I am restoring an old TRC-455, and want to align it by Sams. I have a Tek
scope,
but a standard 10x probe. Do I need a probe with a certain bandwidth?

Vinnie S.