[Milsurplus] 102E receiver comparison GRC-9

[Richard Brunner]

I have both, and don't see much difference.  The Chinese receiver design
was based on the GRC-9, and is very similar.  Both are very stabile.
Any instability would be due to power supply problems.  The GRC-9 uses
selenium rectifiers forward conducting to regulate the filaments, and
they do not age well, increasing internal resistance with use and age.
Replace them with silicon diodes forward conducting, or regulator chips,
and the GRC-9 is rock stabile. The 102E set was only used with
batteries, but I built an ac supply, and it is also rock steady.

The 102E transmitter drifts badly on VFO due to heat in the small box,
but without the box it is very acceptable.

Richard, AA1P

On Wed, 2012-01-11 at 22:26 -0800, Hue Miller wrote:
> Current 'Electric Radio' has article on China 102E receiver.
> Sez stability of both HFO and BFO are superior to GRC-9.
> Why is this, anyone?
> I also see an article on a BC-106, GRC-9, 102E power supply,
> that instructs to adjust GRC-9 xmtr filament to 6.6 volt.
> Since the tube operates perfectly well at 6  volt, isn't this a
> longevity hazard to the scarce 2E22 bottle?
> Also the HV supply seems to depend a whole lot on capacitor
> charging toward peak. It uses a 750 vct xfmr with fullwave
> 2-diodes with capacitive input. I suppose that would put it up
> around 450 volts D.C.    I would have used a  550-600 volt
> xfmr in a 4 diode bridge. Old school.
> If the GRC-9 second IF was a 1L4 instead of the 1R5 IF/
> BFO dualpurpose, would the IF section have greater gain?
> -Hue Miller