[AMRadio] 866 vs solid state

[Rob Atkinson]

That's a known prob with the 500 (fuses blow; ops used to put in
higher current fuses, a boo boo) the fix according to an article in ER
is to use thermistors in series with the l.v. primary for the plate
supply.  It was written about in ER back around 1996 if I remember
right.
the inrush can be rather substantial but varies widely depending on
where in the AC cycle you happen to be the instant the primary circuit
is completed.   The author of the article reported that with the right
thermistors he could go back to the stock rated fuses and save his
power supply iron.  I don't have my ERs with me so unfortunately I
can't tell you the issue and page.


73

rob
K5UJ

On Thu, Jun 14, 2012 at 8:12 AM, CL in NC <mjcal77 at yahoo.com> wrote:
> Has anyone had problems with replacing 866's with their SS equivalents in XMTR's that turn on the plate supply  to transmit, and blowing the plate transformers line fuse?  Did the 866's give a micrroseconds of  turn on resistance that did not hit the filter with the full 2100 intstanly?  This is occuring occasionally with a Johnson  500.  The filter bank is not stock, now is 33uf at 4500VDC and all caps are good.  The 5-25H swinging choke was replaced at one time with a 10H fixed.
>
> Charlie, W4MEC in NC