Well you are the amplifier guru. ?Let me see if I can first find a replacement now that I¡¯m interested in getting these things going.?
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On Oct 10, 2018, at 5:10 PM, Pete Manfre <
pmanfre@...> wrote:
Wheat range do you need¡ I have some I made that are 30mhz to 8ghz
Pete
On Wed, Oct 10, 2018, 5:00 PM Peter Gottlieb <
hpnpilot@...> wrote:
Thanks for that background, just the kind of info I was curious about.?
If I can locate a proper replacement YTO for that first unit it would be great and now knowing where else it is used is a big help. I do have an extra 8568 but don¡¯t want to pull the YTO from it. The fault is that the output amp is bad so the output is very low. I did try making up an amp but never got it to work right over the full freq range.?
On Oct 10, 2018, at 4:45 PM, pianovt via Groups.Io <
pianovt@...> wrote:
Peter,
There is a business reason the two meters have such different RF hardware. The original design was based on the 8558 spectrum analyzer plugin. That plugin was already quite old by the time the 8970A came out. Noise figure meters are a very small market, so the meter had to use parts from something that's made in higher volume. As a result, the later 8970s used some hardware out of the 8590 series spectrum analyzers. At the same time, the frequency range was extended because it was easy to do with the parts out of the 2.9 GHz spectrum analyzers.
The YTO in the old units is the very common 2-4GHz oscillator from the 8558, 8568, and some 8350 sweeper plug-ins. You should be able to find one that is similar enough. Also, unlike the EYO oscillator, those old ones don't break often. They can be found.
Once you get the thing(s) running, check the backup battery. If it runs low, you will see some error codes and lose some calibration data.
Vladan
