[R-390] HP-606* vs URM-25*?

[Roy Morgan]

At 04:39 AM 1/18/2005, ELDIM wrote:
>Hello Tom & Crew,
>The HP-606A is definitely a step up from the vintage AN/URM-25(*) series
>Signal Generators.

I agree, but:

>... The
>606B was another step up (from the 606A) but required the HP 8708A 
>Synchronizer that provided PLL plus some more amenities.

The synchronizer was not required.  The B version of the generator had very 
few differences compared to the A. The ones that I can think of are:
  - facilities to use the synchronizer: DC voltage output proportional to 
the dial setting, a variable capacitance in the oscillator L/C circuit, and 
input/output connectors for the needed signals.
  - possibly a changed RF output stage to avoid the danger of short tube 
life if you run it at the max output level.
  - possibly some solid state parts in the power supply

By the way, the later versions of the HP-608 also could use the 
synchronizer.  With both the 606B and the later 608's the synchronizer gave 
you essentially crystal control frequency stability, FM capability and 
other esoteric features.

>  Of course, you can use it without the
>synchronizer and essentially you still have a 606A.

Exactly.

>... I now use the 8640B which is the "cats meow".

I don't have one yet, but I understand that the prices are coming down 
steadily on this one.  The 8640 will do about all you ever need a signal 
generator for. Except be repairable if you blow out the output solid state 
hybrid module by transmitting into it with a transceiver.

>  There are a lot of other signal generators that fill the bill
>as well.

My very favorite is the General Radio 1001A Standard Signal 
Generator.  Old, heavy, pretty simple, has odd output impedances, but oh, 
so nice to run. Like the door on a Rolls, it goes Klunnkkk when you change 
bands.

Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
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