[Amps] Microwave oven door glass - shielding?

[Roger (K8RI)]

On 10/22/2013 12:26 AM, Jim Barber wrote:
> Hi Ron,
>
> On 10/21/2013 7:05 PM, KA4INM wrote:
>>    On 10/21/13 18:15, Jim Barber wrote:
>>
>>> Has anyone had experience using microwave oven door glass as a shielded
>>> viewport for an HF amp? Any ideas about attenuation at HF frequencies?
>>
>>> I'm considering a three-tube 3500ZG amp as one of my winter projects,
>>> and was thinking it would be fun to show the tubes with their cheery
>>> cherry glow.
>>
>>    How may output Watts will you be producing?
>>    (or are you just going to detune the plate until everything turns red)
>
> 375 watts carrier, 1500 watts PEP. That will get 2 tubes orange with any
> compression at all. I was thinking 3 tubes because 2 seems to be close
> to the edge for true legal limit operation. Two would be easier to deal
> with from the filament  transformer and choke side, that's for sure.

The microwaves are far more efficient at heating flesh than most ham 
frequencies. The most sensitive range is 28 through the 220 band.
http://hintlink.com/power_density.htm
You feed the average power at the antenna plus antenna gain multiplied 
by the duty factor.  20% for SSB and 40% for CW while other modes are 100%

Look at the exposure charts Vs frequency and if you run much ERP on 2 it 
needs to be high and well away from your neighbors.

The same would be true of RF leakage.

73

Roger (K8RI)
>