Softrock Lite 6.2
Adventures in Electronics and Radio
Elecraft K2 and K3 Transceivers
High Pass Filter
The Z10023A is
a receive-only 7th order elliptical high pass filter.
The filter is normally provided to reject 1700 KHz and
below whilst passing 1800 KHz and higher frequencies with minimum loss. On a
per-application basis, other frequency responses may be provided. Please contact
Clifton Laboratories if a custom frequency response is needed.
The typical response of a Z10023A filter, with 1800
KHz pass is illustrated below. At the highest AM broadcast frequency assigned in
the US, the filter provides 45 dB attenuation. At 1800 KHz, the typical
insertion loss is 1.5 dB.
Z10020B Band Reject Filter and Z10023A Filter
The plot below overlays the frequency response of a
Z10020B band reject filter and a Z10023A high pass filter. Three points of
interest are displayed:
- In the area between 1500 and 1700 KHz, the Z10023A
provides greater attenuation.
- The Z10023A is an elliptic filter which means it has
ripples in both the passband and stopband; this is price paid for a steeper
transition from stop to pass frequencies. The worst case rejection in the
medium wave AM band is 40 dB. In all but rare cases, 40 dB will provide more
than adequate signal rejection.
- The Z10020B is a band reject filter and hence passes
frequency above and below the medium wave band; the Z10023A is a high pass
filter and rejects all frequencies below the corner frequency. Hence
reception below the medium wave band is not possible with the Z10023A
filter, unlike the Z10020B.
and Z10023A High Pass Filters
The plot below illustrates the performance of a Z10022A
Chebyshev high pass filter and a Z10023A Elliptic high pass filter. The Z10022A
filter has much greater attenuation (exceeding 100 dB at some frequencies) but a
gentler transition between stop and stop bands. The Z10023A elliptic filter
provides lesser attenuation in the stop band, 40 dB in the worst case, but a
sharper transition between pass and stop frequencies.
Which Filter to Use?
- If you desire to listen to frequencies below the
medium wave band, the Z10020B is the correct solution. Or, a Z10024A
low-pass filter may be used. The difference is that the Z10020B can be used
for both longwave and shortwave reception, whilst blocking medium wave
signals. The Z10024A is usable only for longwave reception.
- If the undesired medium wave signal is on a frequency
of 1400 KHz or lower, and if you require more than 40 dB attenuation, a
Z10022A filter is the best choice.
- If the undesired medium wave signal operates between
1400 and 1700 KHz, the Z10023A filter is the best choice.
- Both the Z10022A and Z10023A filters block signals
below the medium wave band and hence cannot be used for longwave reception.
For longwave reception, a Z10020B or Z10024A filter will be required.
Pricing and Options
Pricing for the standard Z10023A elliptic high pass filter (50 ohm / BNC
connectors / Indoor enclosure) is $77.50
Domestic US shipping via Priority Mail is $7.50. Please contact Clifton
Laboratories for international shipping.
Z10023A is to be shipped to a location within the Commonwealth of Virginia,
please add 5% sales tax.
Opt U: UHF connectors, silver/Teflon (import) with interior hoods: $12.50
Opt U*: UHF connectors, import, nickel plated, no hoods: $8.00
Opt N: Type N connectors, with interior hoods $12.50
Opt S: SMA connectors. $12.50
Opt WSFL: Hammond 1590WSFL flanged weatherproof enclosure $14.00
Opt WSF: Hammond 1590WSF flanged weatherproof enclosure $18.00
Opt 75: 75 ohm impedance instead of 50, built with 50 ohm connectors--no
Opt 75N: 75 ohm impedance with 75 ohm Type N connectors: $22.50
The difference between Option WSFL and WSF is the flange location. Option WSFL
has the flange on the enclosure lid and option WSF has the flange on the
enclosure base. The weatherproof enclosure photograph at the top of the page is
of the WSFL enclosure.
Options WSFL and WSF come with gasketed hardware - the 6-32 and 4-40 screws have
recessed grooved heads with a Buna-S gasket to reduce water ingress.
These filters are assembled as orders arrive and most
options will require an additional order interval. Normal order interval is one
Payment may be made with a check or money order payable to
Clifton Laboratories at the address on the top of this page, or via PayPal to
If ordering a filter, please also send a separate E-mail with your order
specifics and contact information.