The AM Forum

Anyone been able to track down where to get the the two large electrolytic caps for the DX-100?

I checked Antique Electronics Supply and my normal vendors, unless I overlooked something they are not listed.

Thanks!

73 Bruce W1UJR

Hi, Bruce...I used a pair of 100mf / 450v in two DX-100B's with great success.  I DID NOT solid state the high voltage supply in either of them.  The high voltage with tube rectifiers is generally around 800 volts, leaving enough voltage head room.  When the HV supply is solid stated, the increase in voltage leaves insufficient head room for those caps.  Hope this helps.

Hi Bruce,

I had a similar issue with the Seneca.  I used a couple 100mmf caps with a 47 mmf across each one (all axial lead types).  The new caps were still less than half the space of the old ones.  With the removal of the old caps, I also had room for the PTT relay.  

Take care and TNX for the help last weekend.
P

I usually see some at Hostraders Bruce.
Try Hosfelt or Digi Key if you can't wait.

Hi Bruce,
 Im plenty of those caps!  (100mf/450 V) please e-mail me If you want some!

Bruce,

RF Parts,  in CA carries a Twist Lock TVLU1775 -- 125 uf @ 500 V for $ 20.00 ea.  YES  expensive.  I used some of their 125/450 V Twist Locks,  which they no longer have in stock.

Were I to do this again on my DX-100,  would leave the stock ones in place,  and disconnect them.  Then would wire some snap-locks ( or similar ) under the chassis.  Would be much less $$ and still would look stock ... Lotsa room under the chassis, and the loss of convection cooling of the under-cjhassis caps should not be a prob at all.

73  Good Luck ... I sure do like the DX-100's   FB  Rig     Vic   KF6RIP

I got mine from Newark. Mallory and other companies make capacitors which fit exactly into the existing place - with 450 WV/500 Surge rating. Remove the old capactitors and their twist lock bases, and get the type that use a small clamp (order with capacitor to fit). The clamp fits the same two mounting holes as the old plate. I put some extra wrap of stiff PET film (Mylar) around the cap which has case elevated so that if the clamp were to dig into the blue plastic wrap on the cap, it won't cause fireworks. Also be sure to adjust the height of the caps in the clamp so that they are lifted a tiny air gap above chassis there, just good practice. I don't touch the caps when it is running, although its only 400 Volts on the second one, and the heavy plastic cover is probably more than adequate.

Also, when I solid stated the HV, the HV rose to 800 VDC exact, and it doesn't waiver much when modulating or keying as it used to. The trick to keeping the caps happy is to get rid of the tap to the modulator screens off the bleeder and run it from the LV supply through a relay, as Timtron has mentioned in some notes. With 400 volts on each cap, rated for 450/500 WV they will have plenty headroom even with new rectifiers. Before removing the screen wire, I ran it for a while with 350/450 distribution and worse during modulation, and the caps held up, new ones should, due to the surge rating.

Thanks guys, found the caps from your suggestions.

Now I just need to find time to install.

This board is a such a great resource, the collective knowledge here is amazing!

73 Bruce W1UJR



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Bruce - For what it's worth, two of my DX-100's have had their HV caps replaced with 100uf@450VDC without any incidents. One of them even has solid state LV and HV rectifiers in it, and makes exactly 800VDC.

After the twist lock caps in my DX100 shorted and blew the fuse I called AG Tannenbaum and got a couple of 100MFD axial lead caps. Mounted them under the chassis on a couple of terminal strips, left the old ones in place for looks. Works just fine

Tnx again guys!

Joe, before the summer static takes it out, when are you going to be on 160?

-Bruce



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