[Hammarlund] HX-500 trials

[Kenneth G. Gordon]

On 26 Apr 2016 at 18:38, Richard Knoppow wrote:

>      There is something strange about this.

Boy! I certainly agree with you, Richard! :-(

> The ratios of correct to 
> measured voltages vary.

Yes. Odd.

> Of course, if the voltages are wrong the 
> currents will be wrong too which may account for it.  I found a handbook 
> and schematic at Rigpix. The instruction book states the voltages are to 
> be measured with a 20K ohm/V meter so I don't think using the wrong sort 
> of meter will account for it.

No.

> However, if you do have another meter or 
> can borrow one it would be worth checking just to make sure the meter 
> itself is reading correctly.

Agreed.

>     It would be interesting to know what your line voltage is. If you 
> said I missed it.

So did I. What is it?

>     The difference in DC resistance of the chokes is probably normal 
> tolerance.

Yes, it is.

> Also note the HV choke is a swinging one intended to provide 
> some regulation to the supply.

Yes, again.

Now, there are several things about the stuff below that makes me wonder:

> > AC voltages out of the transformer are 900 VAC, 350 vac, 6.8 vac.

OK. Here is one: the AC voltage is 900 VAC, yet the DC voltage is also 900 VDC? Unless 
things are exactly "correct", this cannot be so. There MUST be some differences between 
these two voltages.

> > Filter chokes test OK -- although I don't have my LCR bridge. 

Don't need one: an ohm-meter will do for this purpose.

> > According to the schematics, the HV choke should have a resistance of 
> > 160 ohms, mine is 172.  LV choke should be 250 ohms, mine is 271.

Those are within tolerances. However, here is a problem: Assuming that 900VAC output is 
connected to a full-wave rectifier, the DC output voltage at the rectifier, before it ever 
reaches a filter will be 1.414 X 900 or 1272.6 VDC. 230 mA drawn through your choke of 
170 oms would mean a drop of only 29.2 VDC. THis is still over 1200 VDC. 

Are the rectifiers solid-state diodes? If so there is very little voltage drop with those. If it is a 
tube or tubes, then there is significant voltage drop across those, unless they are mercury 
vapor rectifiers or argon types (3B28).

> > LV circuit is a CLC filter.  At the output of the LV rectifier, 
> > voltage is 380 vdc, should be 270.

350 X 1.414 = 494.9 VDC, 320 X 1.414 = 450 VDC plus

The whole thing is weird...

Ken