The AM Forum

..hi from tim...picked up a very nice apache, very clean, chrome knobs...25bux at a hamfest...i was told there was no vfo...well, there is...but..the thing is transmitting on it's harmonic freq...vfo, or crystal, it transmits a 3590 rock, on 7180...same deal with the vfo..twice the rock freq, or vfo reading...ideas?...btw, bandswitch is in the right position.....thanks..tim..sk..

..brian, well, it is doing it, in the crystal position, as well...i'm thinking something in the "cage", something is telling the old girl, it is on 40...
...tim...sk..

Before ripping into it, check the band switch linkage to the rotary switch in the driver section (middle compartment). Verify that when the front panel band switch is set to 80 meters, the rotary switch in that compartment is also set to 80 meters.

Also check the VFO band switch and the linkage to it, make sure it hasn't slipped or somebody hasn't messed around with the linkage and got things out of sync with the band switch.

I don't think disabling the constant filament in the VFO is good. If you don't mind waiting for the VFO to settle down after first turn on in a cold shack, or chasing yourself with the freq counter during a QSO.
Apparently not a fire hazard. Makes sure it's fused though....just in case.
If the knobs are in good shape, you got a very nice deal for $25.....Ham fests are still a good thing.
I would suggest to drive the modulators with an external mic processor/amplifer with an output transformer hooked up backwards to be rid of the 'scratchy Apache' sound. If you have lots of time and like the frustration of working through the bad solder joints and wiring of the previous builder, then rebuild the mic pre-amp and driver. There's a lot of info here for the mods.
Some folks may cringe at my approach, but it's a lot faster and the audio is out of this world.
Fred

I just finished repairing the VFO in my Apache, (bad filament xformer). But one thing that I did do whilst in the repair mode was checking the linkage and the associated band switches. The levers(?) used to turn the band switches are sheet steel peaned to a bronze bushing. These have a tendancy to slip and twist over time. Check your schematic vs all switch positions to make sure they are operating the proper band at the proper position.

pic of the rig..outta focus...it is in very clean shape...tim....sk..

???

Sure wasn't my experience - nor that of many others - with the Mohack.  Probably the worst receiver I've ever had, except for the MR-1 Comanche.  Poor stability, poor IF selectivty shape factor, nasty distortion in both AM and SSB, the worst AGC ever, and unneccesarily complex. 

There was a 3-part article in ER some years ago correcting all the design problems with this radio.

It *is* pretty though.

Slow attack and fast release - the exact opposite of what's needed.  Makes for a lot of thumping and overshoot.

Perhaps yours has benefited from the many mods necessary for an acceptable result.

Excessive RF and IF gain will not help out either. The sensitivity of the receiver is determined by its noise figure, not gain.

I didn't care for my NC-303 but it definitely ran rings around the RX-1 especially on the higher frequencies. The first time I listened to the RX-1, I thought the speaker I was using had a cracked/ripped cone.

All back issues of Electric Radio are still available from them. You can buy individual issues, a 1 year bundle, or a 4 year bundle.
http://www.ermag.com/index.cfm?v_link=back_issues&v_product_type_name=Back%20Issues

For Electric Radio article searches, you can go here:
http://home.wi.rr.com/n9oo/ersearch.html

I wonder about copyright infringment if you copy and post those articles on your website Brian??????

That depends on the publish date of the manual(s).  The copyright law changed, but I don't remember when.  Many of the old manuals on BAMA are considered public domain.  Those that are not won't be on the site.  That is why you don't see some Collins manuals there.  The Collins Collectors site is the only place that some of their manuals can be found.

Check with your friendly copyright attonery.

Barry no longer owns ER and the present owner has objected to posting of articles from his magazine.  

As far as BAMA is concerned, the presence of a link here does not necessarily say anything one way or another about copyrighted content on BAMA.  Most of the manufacturers for which BAMA has manuals are out of business and arent around to object.  Many manuals aren't even copyrighted.  And last, many are in the public domain and/or the owners have given permission for free distribution.

I am pretty sure that if anything was on BAMA that a copyright holder objected to, it would be taken down by K4XL in short order.  

What is your point  ??? ???

..does anyone have any input, as to my apache..?..
  tim..sk...

No, Tim, it's much more fun to argue about OT minutae ;D

Seriously, get at it with a scope and see where it's doubling.  Perhaps the final, maybe the driver.  Bet one of the bandswitch wafers is out of sync by one position - or it was wired wrong to begin wiht.