Active8 wrote:

i've found out from my reading that pin diodes are only used as attns
and switches down to about 10MHz. i'm wondering if i can use another
type of diode as an attn or switch at lower freqs. i don't recall ever
hearing that.

i think i've seen common diodes (maybe gen purpose signal diodes) as RF
switches and the passive DBM can be used as an attn, though i'm not sure
about the freq range for the DBM attn.

I use 1N4007 (PIN) AGC diodes in a 1.8 to 29.7 MHz
homebrew ham-band receiver at IF frequencies of
8.5 MHz and 3.4 MHz. They are in shunt with an
impedance level of 50 ohms.

PIN diodes have an intermodulation problem when
the forward bias is right at the threshold of
conduction. Ordinary diodes are much worse. At
higher/lower forward bias levels this effect
quickly goes away.

In order to assure that the 20 dBm third-order
intercept point of the receiver is not degraded by
this effect at the critical diode bias point, I
use three 1N4007s in series at each of the three
locations (verified by measurement).

A picture of this receiver is at QRZ.COM (W0IYH)

Bill W0IYH