EXHIBIT 10.35j

                         REVOLVING LOAN MASTER AGREEMENT

     REVOLVING  LOAN  MASTER  AGREEMENT,  dated as of  November  19,  2001 (this
"Agreement"),  by and  among  Motient  Holdings  Inc.  (formerly  known  as AMSC
Acquisition Company, Inc.) (the "Borrower"), Motient Corporation (formerly known
as American Mobile Satellite  Corporation)  (the "Parent"),  Hughes  Electronics
Corporation ("Hughes"), Singapore Telecommunications Ltd. ("Sing Tel") and Baron
Capital  Partners,  L.P.  ("Baron")  (each  of  Hughes,  Sing Tel and  Baron,  a
"Guarantor" and collectively, the "Guarantors").

                              W I T N E S S E T H :

     WHEREAS, the Borrower is party to the Revolving Credit Agreement,  dated as
of March 31, 1998 (as amended,  the  "Revolving  Credit  Agreement"),  among the
Borrower,  the Parent, the financial  institutions party thereto,  as Banks (the
"Banks"), Morgan Guaranty Trust Company of New York, as Documentation Agent (the
"Documentation  Agent"),  and Toronto Dominion (Texas),  Inc., as Administrative
Agent (the "Administrative Agent");

     WHEREAS, loans made to the Borrower by the Banks under the Revolving Credit
Agreement in the aggregate  principal  amount of $77,250,000  are outstanding at
the date hereof (the "Loan");

     WHEREAS, Hughes has guaranteed the punctual payment when due of the Tranche
A Loans of the Borrower  under the Revolving  Credit  Agreement  pursuant to the
Guaranty, dated as of March 31, 1998 (the "Hughes Revolving Guaranty"),  made by
Hughes to the  Administrative  Agent, for its own benefit and for the benefit of
the Banks;

     WHEREAS,  Sing Tel has  guaranteed  the  punctual  payment  when due of the
Tranche B Loans of the Borrower under the Revolving Credit Agreement pursuant to
the Guaranty,  dated as of March 31, 1998 (the "Sing Tel  Revolving  Guaranty"),
made by Sing Tel to the  Administrative  Agent,  for its own benefit and for the
benefit of the Banks;

     WHEREAS,  Baron has guaranteed the punctual payment when due of the Tranche
C Loans of the Borrower  under the Revolving  Credit  Agreement  pursuant to the
Guaranty,  dated as of March  31,  1998 (the  "Baron  Revolving  Guaranty"  and,
together with the Hughes Revolving Guaranty and the Sing Tel Revolving Guaranty,
the "Revolving Guarantees"),  made by Baron to the Administrative Agent, for its
own benefit and for the benefit of the Banks;

     WHEREAS,  the Parent has agreed to reimburse each Guarantor for any payment
made by such  Guarantor  under its  Revolving  Guaranty  pursuant  to a Guaranty
Issuance  Agreement,  dated as of March  31,  1998 (as  amended,  the  "Guaranty
Issuance Agreement"), by and among the Guarantors, the Parent and the Borrower;

     WHEREAS, the Parent granted a security interest to Hughes, as agent for the
Guarantors (the "Guarantor Agent"), for the ratable benefit of the Guarantors in
and to certain collateral, including 9,757,262 shares of common stock, par value
$0.01 per share (the "XM  Shares"),  of XM Satellite  Radio  Holdings  Inc. ("XM
Radio"),  to secure  its  obligations  under  the  Guaranty  Issuance  Agreement
pursuant to the Reimbursement  Security and Pledge Agreement,  dated as of March
31, 1998 (the "Reimbursement  Security  Agreement"),  between the Parent and the
Guarantor Agent;

     WHEREAS,  the Borrower has defaulted on its  obligations to the Banks under
the Revolving Credit Agreement,  including,  without  limitation,  by failure to
apply certain Net Cash  Proceeds  received  from Aether  Systems,  Inc. to repay
loans in accordance  with the Asset Sale Waiver dated as of October 20, 2000 and
by the Borrower's  failure to make an interest  payment in respect of the Senior
Notes;

     WHEREAS,  on November 6, 2001, the Banks declared the Loans  (together with
all interest  accrued  thereon) to be immediately due and payable,  and demanded
that the Borrower and the  Guarantors  honor their  contractual  obligations  to
repay the Loans and all other amounts due under the Revolving  Credit  Agreement
in full;

     WHEREAS,  the  Borrower is unable to repay the Loans and all other  amounts
due under the  Revolving  Credit  Agreement  in full and the Parent is unable to
honor its obligations to the Guarantors under the Guaranty Issuance Agreement to
reimburse the Guarantors for their  payments  under their  respective  Revolving
Guarantees;

     WHEREAS,  the Reimbursement  Security Agreement permits the Guarantor Agent
on behalf of the  Guarantors to foreclose  upon the XM Shares as a result of the
failure by the Parent to reimburse the Guarantors and the Parent acknowledges it
has and will have no defenses to such foreclosure;

     WHEREAS,  on November 15, 2001,  the Borrower  sold,  at the request of the
Guarantors, 500,000 XM Shares for an aggregate net amount of $4,749,841.66;

     WHEREAS,  the Guarantors  have succeeded to the rights of the Banks against
the Borrower under the Revolving Credit Agreement  following payment on November
14, 2001 by the Guarantors to the Banks pursuant to the Revolving  Guarantees of
the Loans and all other amounts due under the Revolving Credit Agreement; and

     WHEREAS,  the Parent  has  offered to  transfer  ownership  of XM Shares in
satisfaction  of the  obligations  of the  Parent  under the  Guaranty  Issuance
Agreement and the  Reimbursement  Security  Agreement and the obligations of the
Borrower  under the  Revolving  Credit  Agreement to the  Guarantors  in lieu of
foreclosure upon such XM Shares subject to the terms and conditions contained in
this Agreement;

     WHEREAS,  concurrently  with the execution of this  Agreement,  the parties
hereto will enter into a Term Loan Master Agreement, dated as of the date hereof
(the  "Term Loan  Master  Agreement"),  relating  to the Term  Credit  Agreement
described therein;

     NOW,  THEREFORE,  in  consideration  of the  premises  and  the  agreements
hereinafter contained, it is hereby agreed as follows:

1.   Recitals.  Each of the parties hereby acknowledges and agrees that each and
all of the  recitals  set forth above are true and correct and are  incorporated
into this Agreement by reference.

2.   Definitions. Capitalized terms used herein and not otherwise defined herein
are used herein as defined in the Revolving Credit Agreement.

3.   Assignment of the XM Shares.  (a) In full satisfaction of its obligation to
reimburse  Hughes for Hughes' payment under the Hughes Revolving  Guaranty,  and
the Parent's and the Borrower's obligations to Hughes under the Revolving Credit
Agreement, the Guaranty Issuance Agreement, the Reimbursement Security Agreement
and the Tranche A Loans, the Parent assigns, transfers,  conveys and delivers to
Hughes 6,010,936 XM Shares (the "Hughes Shares"), free and clear of all Liens.

(b) In full  satisfaction of its obligation to reimburse Sing Tel for Sing Tel's
payment  under  the  Sing  Tel  Revolving  Guaranty,  and the  Parent's  and the
Borrower's  obligations to Sing Tel under the Revolving  Credit  Agreement,  the
Guaranty  Issuance  Agreement,  the  Reimbursement  Security  Agreement  and the
Tranche B Loans, the Parent assigns, transfers, conveys and delivers to Sing Tel
781,765 XM Shares (the "Sing Tel Shares"), free and clear of all Liens.

(c) In full  satisfaction  of its  obligation  to  reimburse  Baron for  Baron's
payment under the Baron Revolving Guaranty,  and the Parent's and the Borrower's
obligations to Baron under the Revolving Credit Agreement, the Guaranty Issuance
Agreement,  the  Reimbursement  Security  Agreement and the Tranche C Loans, the
Parent  assigns,  transfers,  conveys and delivers to Baron  1,001,563 XM Shares
(the "Baron Shares"), free and clear of all Liens.

4.   Closing.  Subject to the terms and conditions contained herein, the closing
for the sale and  purchase of the XM Shares (the  "Closing")  shall occur at the
offices of Weil,  Gotshal & Manges LLP,  767 Fifth  Avenue,  New York,  New York
10153 at 10:00 A.M.  New York City time as  promptly as  practicable,  but in no
event later than the third Domestic  Business Day,  following  execution of this
Agreement by the Borrower, the Parent and each of the Guarantors,  or such other
location,  time or date as may be agreed to in  writing  by the  Parent  and the
Guarantors (the "Closing Date").

5.   Transaction on the Closing Date. At the Closing:

(a) the Parent  will  deliver,  or cause to be  delivered,  to Hughes the Hughes
Shares, together with duly executed stock powers in favor of Hughes;

(b) the Parent will deliver, or cause to be delivered,  to Sing Tel the Sing Tel
Shares, together with duly executed stock powers in favor of Sing Tel;

(c) the  Parent  will  deliver,  or cause to be  delivered,  to Baron  the Baron
Shares, together with duly executed stock powers in favor of Baron; and

(d) the  Borrower  will pay to each  Guarantor  the amounts set forth in Section
5(d) of the Term Loan Master Agreement.

6.   Transfer of Registration Rights. (a) The Parent hereby transfers to Hughes,
Sing Tel and Baron the "Shelf  Registration"  rights  (the  "Shelf  Registration
Right")  under  Section 2.2 of that certain  Amended and  Restated  Registration
Rights Agreement,  dated as of August 8, 2000 (the "XM Registration Agreement"),
by and  among XM  Radio,  the  Parent  and the other  parties  thereto,  and the
"Piggyback   Registration"  rights  (the  "Piggyback  Registration  Right"  and,
together with the Shelf  Registration  Right, the  "Registration  Rights") under
Section 2.3 of the XM Registration  Agreement associated with the Hughes Shares,
Sing Tel Shares and Baron Shares,  respectively,  and all rights associated with
such Registration  Rights. Such Registration Rights shall also be subject to the
limitations set forth in the XM Registration Agreement.

(b) The Parent  agrees to  promptly  notify XM Radio that such  transfer  of the
Registration  Rights has  occurred  and upon the request of any  Guarantor,  the
Parent will execute such further documents and instruments  reasonably necessary
to vest such rights in such Guarantor.

7.   Representations and Warranties of the Borrower.  Each of the Parent and the
Borrower hereby represents and warrants to each of the Guarantors that:

(a)  Organization  and Good  Standing.  Each of the Parent and the Borrower is a
corporation duly organized, validly existing and in good standing under the laws
of the State of Delaware and has all requisite  corporate power and authority to
own,  lease and  operate  its  properties  and to carry on its  business  as now
conducted.

(b)  Authorization  of  Agreement.  Each of the Parent and the  Borrower has all
requisite  power,  authority  and legal  capacity to execute  and  deliver  this
Agreement and each other  agreement,  document,  or  instrument  or  certificate
contemplated by this Agreement or to be executed by the Parent and Borrower,  as
the  case  may be,  in  connection  with the  consummation  of the  transactions
contemplated   by  this   Agreement   (together   with   this   Agreement,   the
"Parent/Borrower  Documents"),  and to consummate the transactions  contemplated
hereby and thereby.  This  Agreement has been,  and each of the  Parent/Borrower
Documents  will be at or prior to the  Closing,  duly and validly  executed  and
delivered by the Parent and the Borrower,  as the case may be, and (assuming the
due  authorization,  execution  and  delivery  by the other  parties  hereto and
thereto) this Agreement constitutes,  and each of the Parent/Borrower  Documents
when so  executed  and  delivered  will  constitute,  legal,  valid and  binding
obligations  of the Parent  and the  Borrower,  as the case may be,  enforceable
against the Parent and the Borrower in accordance with their  respective  terms,
subject to applicable  bankruptcy,  insolvency,  reorganization,  moratorium and
similar laws affecting creditors' rights and remedies generally, and subject, as
to  enforceability,  to general  principles of equity,  including  principles of
commercial  reasonableness,  good faith and fair dealing  (regardless of whether
enforcement is sought in a proceeding at law or in equity).

(c) Conflicts;  Consents of Third Parties. None of the execution and delivery by
the Parent and the Borrower of this Agreement and the Parent/Borrower Documents,
as the case may be, the consummation of the transactions  contemplated hereby or
thereby, or compliance by the Parent and the Borrower with any of the provisions
hereof or  thereof  will (i)  conflict  with,  or result in the  breach  of, any
provision  of  the  certificate  of   incorporation  or  by-laws  or  comparable
organizational  documents of the Parent or the  Borrower;  (ii)  conflict  with,
violate,  result in the breach or termination  of, or constitute a default under
that certain Amended and Restated Shareholders' Agreement, dated as of August 8,
2000, by and among XM Radio and the other parties thereto or the XM Registration
Agreement, or any note, bond, mortgage,  indenture,  license, agreement or other
instrument  or  obligation  to which the Parent or the Borrower is a party or by
which  any of them or any of their  respective  properties  or  assets is bound;
(iii) violate any statute, rule, regulation, order or decree of any governmental
body or authority  by which the Parent or the Borrower is bound;  or (iv) result
in the creation of any Lien upon the  properties  or assets of the Parent or the
Borrower.

(d) Ownership and Transfer of XM Shares. The Parent is the record and beneficial
owner of the XM Shares, free and clear of any and all Liens other than the Liens
referred to in the Term Loan Master Agreement and the Recitals  hereto,  and the
Parent has continuously owned such XM Shares since at least October 8, 1999. The
Parent has the  corporate  power and  authority to transfer,  assign and deliver
such XM Shares as provided in this  Agreement,  and such delivery will convey to
the Guarantors  good and marketable  title to such XM Shares,  free and clear of
any and all Liens, except the Liens referenced above.

8.   Representations  and Warranties of the  Guarantors.  Each of the Guarantors
hereby  severally  represents  and warrants to the Parent and the Borrower  that
such  Guarantor  paid  to the  Banks,  pursuant  to such  Guarantor's  Revolving
Guaranty,  all amounts  demanded by the Banks from such  Guarantor as payment in
full of the  Loans  and  all  other  amounts  due  under  the  Revolving  Credit
Agreement.

9.   Releases.  (a)  Subject  to  Section 10 below,  immediately  following  the
closing of the  transactions  contemplated  by this  Agreement and the Term Loan
Master  Agreement,  each  Guarantor  releases  any  and all  Liens  held by such
Guarantor against the Parent,  any Subsidiary of the Parent or any assets of the
Parent or any of the Parent's  Subsidiaries.  Each of the  Guarantors  agrees to
execute  and  deliver  or  file,  at  the  Parent's  expense,  such  termination
statements  and take such other  actions as are  reasonably  necessary to effect
such release.

(b) Each of the Borrower and the Parent hereby  releases and discharges  each of
the  Guarantors,  and  their  respective  subsidiaries,   directors,   officers,
shareholders,  affiliates,  employees, agents and representatives (collectively,
the "Guarantor  Releasees") from any and all claims,  demands,  causes of action
and  liabilities  of any kind  whatsoever,  whether known or unknown,  which the
Borrower or the Parent  ever had,  now has, or  hereafter  may have  against the
Guarantor  Releasees  arising  out of or  relating  to  this  Agreement  and the
Revolving  Credit  Agreement,  and  the  transactions  contemplated  hereby  and
thereby, except for those continuing obligations set forth in this Agreement.

(c) Subject to Section 10 below and any continuing obligations set forth in this
Agreement,  each of the Guarantors hereby releases and discharges the Parent and
the  Borrower,   and  their  respective   subsidiaries,   directors,   officers,
shareholders,  affiliates,  employees, agents and representatives (collectively,
the "Borrower Releasees") from any and all claims, demands, causes of action and
liabilities  of any kind  whatsoever,  whether  known  or  unknown,  which  such
Guarantor  ever  had,  now has,  or  hereafter  may have  against  the  Borrower
Releasees  arising out of or relating to this Agreement and the Revolving Credit
Agreement, and the transactions contemplated hereby and thereby.

10.  Reinstatement  of  Obligations  to  Guarantors.  Each of the Parent and the
Borrower  agrees  that,  if any  assignment  of XM Shares  by the  Parent to any
Guarantor  pursuant to this  Agreement  is at any time  annulled,  avoided,  set
aside,  rescinded,  invalidated,  declared to be fraudulent or  preferential  or
otherwise  required to be refunded or repaid,  or the proceeds of such XM Shares
are required to be returned by any Guarantor to the Parent, its estate, trustee,
receiver or any other  party under any  bankruptcy  law,  state or federal  law,
common  law or  equitable  cause,  then,  to the  extent of such  assignment  or
repayment,  the Parent's liability to such Guarantor under the Guaranty Issuance
Agreement and the Reimbursement  Security  Agreement (and any Lien securing such
liability) and the Borrower's  obligations to such Guarantor under the Revolving
Credit  Agreement  shall be and remain in full force and effect,  as fully as if
such  assignment  or repayment  had never been made,  and the Guaranty  Issuance
Agreement,  the  Reimbursement  Security  Agreement  (and  such  Lien)  and  the
Revolving  Credit  Agreement  shall be reinstated in full force and effect,  and
such prior  cancellation  or surrender shall not diminish,  release,  discharge,
impair or  otherwise  affect the  obligations  of the Parent or the  Borrower in
respect of the amount of such assignment or repayment (or any Lien securing such
obligation), and Sections 9(a) and 9(c) shall become null and void with no force
or effect.

11.  Further  Assurances.  Each of the  parties  hereto  agrees to  execute  and
deliver such other  documents or agreements and to take such other action as may
be reasonably  necessary or desirable for the  implementation  of this Agreement
and the consummation of the transactions contemplated hereby.

12.  Counterparts. This Agreement may be executed in any number of counterparts,
all of which,  taken together,  shall  constitute one and the same agreement and
any party may enter into this Agreement by executing a counterpart.

13.  Notices. All notices and other communications under this Agreement shall be
in  writing  and shall be deemed  given  when  delivered  by hand or by  courier
service,  or upon  electronic  confirmation of facsimile  transmission,  or upon
delivery by certified  mail,  return  receipt  requested,  to the parties at the
following  addresses (or to such other address as a party may have  specified by
notice given to the other parties pursuant to this provision):

                           If to the Parent or the Borrower, to:

                           Motient Corporation
                           10802 Parkridge Boulevard
                           Reston, Virginia 20191
                           Attn: General Counsel
                           Facsimile: (703) 758-6134

                           If to Hughes, to:

                           Hughes Electronics Corporation
                           200 North Sepulveda Boulevard
                           18th Floor
                           MS-154
                           El Segundo, California 90245
                           Attn: O'Donnell Iselin
                           Facsimile: (310) 640-1734

                           If to Sing Tel, to:

                           Singapore Telecommunications Ltd.
                           31 Exeter Road
                           #26-00 Comcentre
                           Singapore 239732
                           Republic of Singapore
                           Attn: Chua Loh Yim Kew (Mrs.)
                           Facsimile: 011-65-8353920

                           If to Baron, to:

                           Baron Capital Partners, L.P.
                           767 Fifth Avenue
                           New York, New York 10153
                           Attn: Mr. Morty Schaja
                           Facsimile: (212) 759-7529

                           With a copy to:

                           Baron Capital Partners, L.P.
                           767 Fifth Avenue
                           New York, New York 10153
                           Attn: Linda Martinson, Esq.
                           Facsimile: (212) 759-7529

14.  Severability.   If  any   provision   of  this   Agreement  is  invalid  or
unenforceable, the balance of this Agreement shall remain in effect.

15.  Governing  Law.  This  Agreement  shall be  governed  by and  construed  in
accordance  with the laws of the State of New York without regard to conflict of
law principles.

16.  Headings.  Headings  are for  convenience  only and  shall not  affect  the
interpretation of this Agreement.


                            [SIGNATURES ON NEXT PAGE]



<PAGE>


     IN WITNESS  WHEREOF,  the  parties  hereto  have  executed  this  Agreement
effective as of the date first written above.

                                    MOTIENT CORPORATION


                                    By:   /s/Walter V. Purnell, Jr.
                                          --------------------------------------
                                    Name: Walter V. Purnell, Jr.
                                    Title:President and Chbief Executive Officer

                                    MOTIENT HOLDINGS, INC.


                                    By:   /s/Walter V. Purnell, Jr.
                                          --------------------------------------
                                    Name: Walter V. Purnell, Jr.
                                    Title:President and Chbief Executive Officer

                                    HUGHES ELECTRONICS CORPORATION


                                    By:   /s/Patrick T. Doyle
                                          --------------------------------------
                                    Name: Patrick T. Doyle
                                    Title:Corp. Vice President, Treasurer

                                    SINGAPORE TELECOMMUNICATIONS LTD.


                                    By:   /s/Tay Chek Khoon
                                          --------------------------------------
                                    Name: Mr. Tay Chek Khoon
                                    Title:Vice President (Satellite Business and
                                          Global Management)

                                    BARON CAPITAL PARTNERS, L.P.
                                    By Baron Capital Management, Inc.


                                    By:  /s/Linda S. Martinson
                                          --------------------------------------
                                    Name: Linda S. Martinson
                                    Title:Vice President & General Counsel



<PAGE>