On Sun, 28 May 2017 08:09:04 +1000, Clifford Heath
wrote:
On 28/05/17 04:35, Jeff Liebermann wrote:
On Sat, 27 May 2017 12:55:02 -0400, wrote:
Look for something that has a built in prescaler. Something like
this:
http://www.ebay.com/itm/Blue-RF-Signal-Frequency-Counter-Cymometer-Tester-0-1-60MHz-20MHz-2400MHZ/172396798620
The basic counter goes from 100KHz to 60MHz. The other ranges use a
prescaler to divide down the input frequency so that it ends up at
less than 60MHz and can be counted.
I have two of those. I bought the second because I thought I'd
broken the first, it performed so badly. They're as bad as each
other.
Thanks. I was thinking of buying some of those. I should have known
as much of the low cost "modules" that I've purchased seem to have
deficiencies as a result of crude design or cost cutting exercises.
To clarify my my comments a little, I was not recommending the
purchase of any of the devices I pointed to on eBay. I meant them as
examples of devices that have prescalers, which was part of the OP's
rant on requiring multiple counters to cover the frequency range. My
comment "Something like this:" usually preceeds something that I
haven't worked with.
If you have a strong and stable signal, it can work ok, but
the input design is poor. The HF and the pre-scaler both
have dual-gate mosfets, but there's no gain control (automatic
or otherwise) and the inputs are paralleled. I've disconnected
the two inputs by cutting a track and soldered on a little bit
of RG-158 to an SMA connector for the high range.
I picked that particular example because it has a drawing of the PCB
showing i/o and controls:
http://i.ebayimg.com/images/g/hBYAAOSwAPVZGlOn/s-l1600.jpg
It has two adjustments labelled "High channel sensitivity adjust"
which I guess would help with the tiggering. Do these controls work,
or were they deleted in yet another cost cutting exercise?
I'd love it if Mike is willing to share some of his counter
front-end wisdom.
The OP has not disclosed how he plans to use the counter. If it's a
bench instrument, that requires precision, I suggest any of the
numerous used HP counters available on eBay.
https://www.google.com/search?tbm=isch&q=hp+universal+counter
Especially the HP 5300 series:
https://www.google.com/search?q=hp+5300+counter&tbm=isch
I have accumulated a fair collection of these and find that used
counters are a far better deal than the eBay instruments, such as:
http://www.ebay.com/itm/Victor-VC3165-Radio-Frequency-Counter-RF-Meter-0-01Hz-2-4GHz-K8M3/122448388056
Incidentally, since the OP is into tubes, my favorite counter is an HP
5248M with genuine Nixie tubes. Middle right above the spectrum
analyzer:
http://802.11junk.com/jeffl/pics/home/slides/lab.html
The pile of 4 plugins under the Glad bag box are the various mixer
type downconverters I previously mentioned. I also have an HP 5245L:
https://www.eevblog.com/forum/repair/repair-of-hp-5245l-nixie-frequency-counter/?action=dlattach;attach=204375;image
Cheap but scarce on eBay:
http://www.ebay.com/itm/HP-Hewlett-Packard-5248L-Electronic-Counter-5254C-Frequency-Converter-15-3-0GHz-/182520538437
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558