[Boatanchors] Speaker Question

[Michael D. Harmon]

I have a bunch of surplus Motorola mobile speakers, both the old 
metal-cased units and the newer Micor-type plastic-cased units.  
According to everything I've been able to find, all these speakers are 
rated at 4 ohms (actually 3.2 ohms).  These speakers are excellent voice 
reproducers, and the intelligibility is far better than a lot of the 
aftermarket (i.e. Radio Shack) so-called mobile extension speakers.  The 
question I have is this:

Most communications receivers (like my Heath SB-102 and National NC-300) 
specify their audio output at 8 ohms.   They all use tube-type audio 
output stages with a small output transformer.  Will it damage these 
receivers to drive a  4-ohm load?  Of course the waveform is a voice 
signal, so the average power output is pretty low (plus with Motorola 
speakers you don't need much power to hear them).

If I were working with a stereo system or a musical instrument amp, I'd 
find a speaker to match the output.  However, I have these speakers, and 
I'd like to use them if they won't hurt my gear.

Thanks for the help.
Mike, WB0LDJ
mharmon at att dot net